{"id":563,"date":"2026-10-02T11:55:44","date_gmt":"2026-10-02T11:55:44","guid":{"rendered":"https:\/\/meratch.com\/blog\/?p=563"},"modified":"2026-10-08T09:30:30","modified_gmt":"2026-10-08T09:30:30","slug":"drought-2026-it-did-not-stop-raining-it-started-evaporating-more","status":"publish","type":"post","link":"https:\/\/meratch.com\/blog\/2026\/10\/02\/drought-2026-it-did-not-stop-raining-it-started-evaporating-more\/","title":{"rendered":"Drought 2026: it did not stop raining. It started evaporating more"},"content":{"rendered":"\n

2026 brought Slovakia its driest start to a year in 65 years, a new national temperature record, and a summer with no match in the measured record. But the data point to something that does not fit the usual story about drought: the main cause was not that we get less and less rain. The main cause is that the atmosphere is getting thirstier. And that determines which measures will work \u2014 and which will not.<\/strong><\/p>\n\n\n\n\n\n\n\n

Part one \u2014 what happened, and why<\/h2>\n\n\n\n

A year that began with an empty store<\/h3>\n\n\n\n

The 2026 drought did not begin in summer. It began in December 2025.<\/p>\n\n\n\n

December 2025 to May 2026 was the driest December\u2013May period in Slovakia in 76 years<\/strong>: 233 mm, or 65 % of the normal. The same record fell for Central Europe as a whole (68 % of normal). We therefore entered the growing season not at zero but in deficit \u2014 the soil profile that crops draw on in July and August was never refilled in spring.<\/p>\n\n\n\n

By 11 September 2026 the year-to-date rainfall total over Slovakia stood at 349 mm against a long-term median of 541 mm<\/strong>, just under 65 %. That is the driest start to a year in the 1961\u20132026 record<\/strong>; the previous minimum belonged to 2003 (401 mm), and 2026 sits a further 51 mm below it. Even the heavy rain of 11 September \u2014 areally the wettest day since the start of summer \u2014 removed less than a tenth of the deficit and did not change the year\u2019s rank in any window longer than a month.<\/p>\n\n\n\n

A summer that rewrote the records<\/h3>\n\n\n\n

Summer 2026 was not the warmest on record in mean temperature \u2014 it came third, behind 2024 and 2022. In heat extremes<\/strong>, however, it stands alone:
<\/p>\n\n\n\n

indicator (summer 2026)<\/td>value<\/td>rank 1961\u20132026<\/td><\/tr>
mean of station maxima<\/td>37.4 \u00b0C<\/strong> (normal 33.0)<\/td>1st \u2014 record<\/strong><\/td><\/tr>
days with Tmax \u2265 35 \u00b0C<\/td>9.7<\/strong> per station (normal 1.2)<\/td>1st \u2014 record<\/strong><\/td><\/tr>
days with Tmax \u2265 38 \u00b0C<\/td>2.9<\/strong> per station (normal 0.1)<\/td>1st \u2014 record<\/strong><\/td><\/tr>
nights with Tmin \u2265 24 \u00b0C<\/td>0.3 per station<\/td>1st \u2014 record<\/strong><\/td><\/tr>
precipitation total<\/td>57 % of normal<\/strong><\/td>2nd\u20133rd driest<\/strong><\/td><\/tr>
absolute maximum<\/td>42.2 \u00b0C<\/strong> \u2014 Doln\u00e9 Plachtince, 6 Aug<\/td>new national record<\/td><\/tr><\/tbody><\/table>
* from operational automatic-station data; official confirmation rests with the Slovak Hydrometeorological Institute. Previous record: 40.3 \u00b0C, Hurbanovo, 20 July 2007.<\/em><\/figcaption><\/figure>\n\n\n\n

Of 70 stations with records longer than 40 seasons, 58 broke their own all-time maximum<\/strong> and 49 their own record for days above 35 \u00b0C. Hurbanovo \u2014 a station with a record going back to 1872 \u2014 recorded a mean summer temperature of 24.3 \u00b0C, 53 tropical days, and 29.9 mm of rain for the whole summer<\/strong>. The previous minimum in 154 years of measurement was 73.2 mm. The longest continuous dry spell there lasted 42 days<\/strong>.<\/p>\n\n\n\n

Heat extremes: it is not only about the days<\/h3>\n\n\n\n
\"\"
Figure 1 \u2014 The summer that rewrote the heat records<\/em><\/figcaption><\/figure>\n\n\n\n

Summer 2026 was not uniform. It rested on two exceptional heatwaves<\/strong> with a nearly normal July between them:<\/p>\n\n\n\n

wave<\/td>days<\/td>peak<\/td>days \u2265 35 \u00b0C<\/td>days \u2265 40 \u00b0C<\/td>tropical nights (total)<\/td><\/tr>
19 Jun \u2013 1 Jul<\/strong><\/td>13<\/td>41.3 \u00b0C (30 Jun)<\/td>9<\/td>2<\/td>
150<\/td><\/tr>
16\u201319 Jul<\/td>4<\/td>36.6 \u00b0C<\/td>2<\/td>0<\/td>13<\/td><\/tr>
29 Jul \u2013 7 Aug<\/strong><\/td>10<\/td>42.2 \u00b0C<\/strong> (6 Aug)<\/td>10<\/td>4<\/td>181<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The August wave was the most intense: on all ten days at least one station exceeded 35 \u00b0C, and on average 80 % of the network passed 30 \u00b0C. On 5 August, 26 stations exceeded 40 \u00b0C at once<\/strong> \u2014 before 2026, the 40 \u00b0C mark had been reached in Slovakia three times in the entire measurement history.<\/p>\n\n\n\n

The heat did not stay in the lowlands. Records fell in the mountains too: Lom nad Rimavicou at 1,018 m<\/strong> recorded 7 tropical days (previous best 3) and 9 tropical nights (previous best 4). Lowlands below 200 m averaged 43 tropical days \u2014 almost half the summer<\/strong> \u2014 and nearly 17 days above 35 \u00b0C.<\/p>\n\n\n\n

The nights, however, were decisive.<\/strong> Bratislava-Koliba recorded 26 tropical nights, six of them with a minimum above 24 \u00b0C<\/strong>; the national record for the highest night-time minimum fell at Skalica on 5 August \u2014 28.4 \u00b0C<\/strong>. And this is where the attribution signal is strongest: tropical nights in Slovakia are now almost 30\u00d7 more frequent<\/strong> than in a pre-industrial climate, while tropical days are \u201conly\u201d 4.3\u00d7 more frequent. For health the first number matters more \u2014 heatwaves kill when the body gets no chance to cool down overnight.<\/p>\n\n\n\n

Heat stress is measured by the UTCI, which combines temperature with humidity, wind and radiation. The average station recorded 116 hours of very strong heat stress<\/strong> (UTCI \u2265 38 \u00b0C) in summer 2026; at Dudince it was 294 hours<\/strong>. At four stations the index passed 46 \u00b0C<\/strong> at least once \u2014 the threshold of extreme heat stress; the maximum of 46.5 \u00b0C was reached at Hurbanovo.<\/p>\n\n\n\n

\"\"
Figure 2 \u2014 Where the heat was genuinely dangerous<\/em><\/figcaption><\/figure>\n\n\n\n

On a European scale, Slovakia sat at the edge of the core. The most days above 35 \u00b0C occurred over the Iberian Peninsula, southern France, Italy and the Balkans; tropical nights concentrated along the Mediterranean coast, where the sea released the heat it had accumulated all summer. The World Weather Attribution analysis of the June European heatwave showed something that applies to us as well: daytime maxima in Europe are rising roughly three times faster than the global mean temperature, and night-time minima about twice as fast<\/strong>. Compared with 2003 \u2014 still the symbol of lethal heat \u2014 today\u2019s daytime heat is about ten times<\/strong> more likely, and night-time heat more than a hundred times<\/strong> more likely.<\/p>\n\n\n\n

What that means in people: the summer of 2022 cost Europe more than 60,000<\/strong> heat-related deaths, the summer of 2023 more than 47,000<\/strong>. The June 2025 wave alone caused an estimated 2,300 deaths in twelve European cities.<\/p>\n\n\n\n

\"\"
Figure 3 \u2014 Rainfall vs.\u00a0evaporative demand, Slovakia, summer 1950\u20132026<\/em><\/figcaption><\/figure>\n\n\n\n

Why this drought was different<\/h3>\n\n\n\n

Here is the core of it. Looking at summer rainfall in Slovakia over the past 77 years, there is no statistically significant trend<\/strong> \u2014 +0.7 mm per decade, with p = 0.87, statistically indistinguishable from zero. The rainfall deficit of summer 2026 was year-to-year variability, of the kind that also occurred in 1976 and 2015.<\/p>\n\n\n\n

What does<\/strong> have a trend, and a strong one, is the atmosphere\u2019s evaporative demand \u2014 potential evapotranspiration. It is rising by 12.5 mm per decade<\/strong> (p = 4\u00b710\u207b\u2076) and in summer 2026 reached 498 mm, the highest value in the entire 1950\u20132026 record<\/strong>.<\/p>\n\n\n\n

The consequence is fundamental. The climatic water balance \u2014 the difference between what falls and what can evaporate \u2014 ended at \u2212343 mm against a normal of \u2212107 mm<\/strong>. In other words: the same rain leaves substantially less water in the soil today than it did four decades ago. Rainfall deficits that used to cause no drought now cause one.<\/strong><\/p>\n\n\n\n

The chain that produced summer 2026 ran like this:<\/p>\n\n\n\n

    \n
  1. An empty store at the start<\/strong> \u2014 the driest winter and spring in 76 years.<\/li>\n\n\n\n
  2. A persistent ridge of high pressure<\/strong> \u2014 subtropical air reached further north than in any of the past 77 years, and the cold troughs that normally interrupt heatwaves appeared on four days in a hundred instead of the usual twenty-four.<\/li>\n\n\n\n
  3. Record solar radiation<\/strong> \u2014 over both Central and Western Europe the surface received more energy than in any of the past 77 years.<\/li>\n\n\n\n
  4. Record evaporative demand<\/strong> \u2014 and the soil dried out so far that actual evaporation nonetheless fell<\/strong> (by 33 mm below normal in Slovakia). The surface switched into a moisture-limited regime: the atmosphere wanted to evaporate more, but there was nothing left to evaporate.<\/li>\n\n\n\n
  5. The feedback<\/strong> \u2014 energy that could no longer go into evaporation went into heating the air instead. 17 W\/m\u00b2 more<\/strong> than usual was diverted into sensible heat. Soil temperature at Hurbanovo reached 27.4 \u00b0C at 5 cm depth in August (+5.1 \u00b0C above normal) and a maximum of 48.8 \u00b0C at 2 cm \u2014 a surface behaving like a hotplate, not like moist ground.<\/li>\n<\/ol>\n\n\n\n

    That last step is why the absolute maxima climbed so high. In a normal summer, part of the energy that drove the temperature to 42.2 \u00b0C on 6 August would have gone into evaporating water from soil and vegetation.<\/p>\n\n\n\n

    And the same feedback closes the loop: heat dries the soil, and dried soil intensifies the heat. Drought and heatwave are no longer two separate phenomena. They are two expressions of one process.<\/strong><\/p>\n\n\n\n

    The European context<\/h3>\n\n\n\n

    Slovakia was not an exception \u2014 it was part of a continental-scale event. Summer 2026 was the warmest in the entire 1950\u20132026 record in 16 European countries and in Europe as a whole<\/strong>. France finished at +3.9 \u00b0C above normal, Italy at +3.1 \u00b0C, Hungary and Austria at +2.7 \u00b0C, Slovakia, Czechia and Germany at +2.2 \u00b0C.<\/p>\n\n\n\n

    \"\"
    Figure 4 \u2014 Summer 2026 in Europe: rainfall, temperature, hot days<\/em><\/figcaption><\/figure>\n\n\n\n

    In rainfall terms the worst affected was Hungary (39 % of normal), followed immediately by Slovakia (53 %). The only country in our neighbourhood that stayed outside the core of the anomaly was Poland<\/strong> \u2014 106 % of normal rainfall and \u201conly\u201d +1.0 \u00b0C. A reminder that the boundaries of such events are sharp, and that a neighbour\u2019s experience need not transfer.<\/p>\n\n\n\n

    \"\"
    Figure 5 \u2014 Four views of the same drought<\/em><\/figcaption><\/figure>\n\n\n\n

    Looking at the situation through the Copernicus European Drought Observatory, four indicators tell the same story from four angles. Soil moisture<\/strong> shows a continuous dry belt from France through the Alps to the Carpathians and the Pannonian Basin. River flow<\/strong> \u2014 the Low-Flow Index, modelled over the river network \u2014 marks the same rivers that carried record-low summer discharges. Vegetation condition<\/strong> confirms that the deficit reached the crops themselves. And the Combined Drought Indicator<\/strong> places much of Central Europe and France in the \u201calert\u201d class, meaning a rainfall deficit that has already progressed through dry soil to damaged vegetation.<\/p>\n\n\n\n

    \"\"
    Figure 6 \u2014 Soil and rivers at once<\/em><\/figcaption><\/figure>\n\n\n\n

    Zoomed to Central Europe, the picture is sharply drawn: Slovakia, Hungary, Austria and southern Czechia deep in the dry range, Poland on the wet side of normal.<\/p>\n\n\n\n

    The World Weather Attribution<\/strong> initiative published an analysis of the April\u2013June European drought in July 2026 that arrived at the same mechanism as our own data. In Western Europe it found no statistically significant long-term decline in rainfall; by its account the drought is driven exclusively by rising evaporative demand. The quantification is telling:<\/p>\n\n\n\n

      \n
    • soil drought<\/strong> is now about 5 times more likely in Western Europe and 11 times more likely in the East<\/strong> than in a climate 1.4 \u00b0C cooler,<\/li>\n\n\n\n
    • the high-evaporation conditions themselves<\/strong> are ~80\u00d7 (west) and ~40\u00d7 (east) more likely<\/strong>,<\/li>\n\n\n\n
    • the intensity of evaporative demand is 7\u20138 % higher<\/strong>,<\/li>\n\n\n\n
    • with a further +1.4 \u00b0C<\/strong>, intense evaporative conditions in Western Europe will be another 10\u00d7 more likely<\/strong> than today.<\/li>\n<\/ul>\n\n\n\n

      One detail matters. In Western Europe the rainfall deficit was a once-in-25-year event. The evaporative demand was a once-in-50-year event.<\/strong> The shortage of rain was unremarkable; the thirst of the atmosphere was not.<\/p>\n\n\n\n

      Our own attribution analysis for Slovakia, built on the three longest station records (Hurbanovo and Bo\u013ekovce from 1872, Liptovsk\u00fd Hr\u00e1dok from 1881), gives the same picture: a summer with this mean temperature, this number of tropical days and tropical nights would have been practically impossible<\/strong> in a pre-industrial climate. Tropical nights are now almost 30\u00d7 more frequent<\/strong>, tropical days 4.3\u00d7. For health impacts the first of those numbers matters more than the second \u2014 it is the absence of night-time cooling that makes heatwaves lethal.<\/p>\n\n\n\n

      What it cost<\/h3>\n\n\n\n

      The impacts were not hypothetical. From phenological observations the Slovak Hydrometeorological Institute reports yields 10\u201340 % lower<\/strong> and failure of spring forest plantings; from hydrology, zero flows on small streams and historically unprecedented summer discharges on the Danube. Across the wider continent, Romania lost more than a million hectares of maize<\/strong>, France recorded its lowest maize harvest in 50 years<\/strong>, several countries imposed emergency water rationing, and low river levels restricted cargo shipping.<\/p>\n\n\n\n

      \"\"
      Figure 7 \u2014 What leaves the store does not return in one season<\/em><\/figcaption><\/figure>\n\n\n\n

      And there is a longer arc behind the single season. The GRACE and GRACE-FO satellites weigh the total water store \u2014 snow, soil moisture, surface water and groundwater together. Over Central Europe that store has been falling steadily since roughly 2015 and now sits some 140 mm below the 2004\u20132009 average<\/strong>. This is the part of the drought that a single wet autumn does not repair.<\/p>\n\n\n\n

      \n\n\n\n

      Part two \u2014 is Slovakia prepared?<\/h2>\n\n\n\n

      We measure well. We have nothing to act on<\/h3>\n\n\n\n

      The answer in one sentence: Slovakia knows how severe its drought is. But it has no document that governs what to do about it, and no authority empowered to act.<\/strong><\/p>\n\n\n\n

      The Slovak Hydrometeorological Institute runs drought monitoring that is professionally sound. An Action Plan for Addressing the Consequences of Drought and Water Scarcity \u2014 H2ODNOTA JE VODA<\/em> \u2014 was approved by the government in 2018 as the first cross-sectoral document on the subject, with a costed requirement of more than \u20ac140 million. Water Act 364\/2004 provides a general framework.<\/p>\n\n\n\n

      What is missing is the connection between them: the action plan is not legally binding and imposes no planning duty on anyone.<\/strong> There are no drought-management plans for regions or river basins, no authority that would declare a state of water shortage and order restrictions, and no public forecast layer \u2014 an outlook weeks ahead rather than a statement of today\u2019s condition.<\/p>\n\n\n\n

      \"\"
      Figure 8 \u2014 Drought preparedness: Slovakia and its neighbours<\/em><\/figcaption><\/figure>\n\n\n\n

      How the neighbours stand<\/h3>\n\n\n\n

      Czechia<\/strong> is furthest ahead in the region, and the difference is institutional rather than technical. The so-called \u201cdrought\u201d amendment to the Water Act (No. 544\/2020), in force since February 2021, introduced drought plans<\/strong> as binding operational documents and regional drought commissions<\/strong> empowered to decide during water shortage. Regional plans were to be drawn up by the end of 2023, and a national plan was assembled from them. The technical layer is supplied by the HAMR<\/strong> system (Hydrology \u2013 Agronomy \u2013 Meteorology \u2013 Retention), developed jointly by the T. G. Masaryk Water Research Institute, CzechGlobe, the Czech University of Life Sciences and the Czech Hydrometeorological Institute, which computes indicators weekly and \u2014 unlike our monitoring \u2014 also provides a forecast<\/strong>.<\/p>\n\n\n\n

      Poland<\/strong> adopted its drought plan (PPSS) by regulation in 2021, making it legally binding. The first version contained mainly general recommendations and a retention agenda; the update running to 2027 is to add concrete measures for individual municipalities and river basins<\/strong> together with an operational dimension \u2014 what to do once drought arrives.<\/p>\n\n\n\n

      Hungary<\/strong>, the worst affected this year in rainfall terms, approved a government action plan on sustainable water management<\/strong> in August 2026. Its centre of gravity is a shift from draining water away to retaining it in the landscape and in the soil \u2014 precisely what Hungary has long lacked.<\/p>\n\n\n\n

      At European level the European Commission is preparing drought-assessment indicators and technical guidelines for drought-management plans under its Water Resilience Strategy<\/strong>, intended to harmonise member-state approaches. The decisive point remains that drought-management plans are not mandatory in the EU<\/strong> \u2014 and it is exactly this that World Weather Attribution identified as the main reason for inconsistent preparedness across the Union.<\/p>\n\n\n\n

      Five priorities that should come first<\/h3>\n\n\n\n

      1. Convert the action plan into a binding instrument.<\/strong> Without a planning duty and a designated authority, any drought document remains a recommendation. The Czech model from 2020 shows this is not especially demanding \u2014 it is a matter of political decision, not technical capacity.<\/p>\n\n\n\n

      2. Add a forecast to the monitoring.<\/strong> The difference between \u201cthere is drought today\u201d and \u201cthere will be drought in ten days\u201d is the difference between reaction and decision. Small water-supply systems fail on the daily peak, not on the annual balance \u2014 and that is exactly where a few days of notice change the outcome.<\/p>\n\n\n\n

      3. Shift measures from water supply to water demand.<\/strong> If drought is driven by evaporative demand rather than declining rainfall, then enlarging storage alone does not solve the problem \u2014 it addresses only one end of it. Equally important are measures that reduce evaporation and increase retention in the soil: soil organic matter, ground cover, agroforestry, wetland restoration, removing sealed surfaces in settlements.<\/p>\n\n\n\n

      4. Measure where decisions are made.<\/strong> Gridded reanalyses and satellite products give a picture, but not an answer to how much water is in this<\/em> field or beneath this<\/em> spring. Combining local sensors with satellite and model data is now affordable both technically and financially.<\/p>\n\n\n\n

      5. Tie the warning to a specific decision.<\/strong> A warning that does not end with \u201cdo this\u201d is not a warning but a piece of information. For a water utility that means the timing of restrictions, activating a backup source, filling a reservoir against the daily peak, booking tankers. For a municipality, watering and planting dates. For a farmer, irrigation dose and timing.<\/p>\n\n\n\n

      What we are doing about it<\/h3>\n\n\n\n

      It is exactly that last step \u2014 from measurement to decision \u2014 that our work at Meratch<\/strong> is built on.<\/p>\n\n\n\n

      DroughtScope (or Droughter)<\/strong> is our product line for drought and flash drought, built on the same platform as our flood product Floodar<\/strong>. That is not a coincidence: baked dry soil has lower infiltration, so the first heavy rain produces higher and faster runoff. Drought and flash flooding are two ends of the same soil-moisture axis<\/strong>, and one data layer serves both products.<\/p>\n\n\n\n

      What already exists and runs:<\/p>\n\n\n\n