By Dr Laura Baker Senior NCAS Scientist in the Department of Meteorology
As we come to the end of the third heatwave of 2025, and a third English water board has announced a hosepipe ban, more and more comparisons are cropping up in the media with the infamous hot, dry UK summer of 1976. Despite occurring nearly 50 years ago, 1976 is still considered a benchmark extreme hot, dry summer, due in particular to its prolonged high temperatures (including a stretch of 16 days above 30 degrees) and severe impacts on water supply. But how similar is this hot summer, so far, to 1976?
Summer so far
We first compare the summer so far, by looking at the June temperature and precipitation anomalies in 2025 and in 1976. The area impacted by the 1976 heatwave had a relatively small spatial extent, with extreme high temperatures in June 1976 confined to the UK, France, Benelux, Portugal and northern Spain with the highest temperature anomalies seen in western France (Fig. 1, top left panel). Much of the rest of Europe experienced colder than average temperatures, especially in eastern Europe. In contrast the high temperatures in June 2025 were more extensive, extending further south and east to include the whole of southern Europe and north Africa (Fig. 1, lower left panel). In terms of precipitation, the negative anomalies in June 1976 extended over the whole of north-west Europe, while the Mediterranean region experienced a wetter than average month (Fig. 1, top right panel). In contrast, June 2025 showed less extreme dry anomalies in north-west Europe, but strong dry anomalies in south-east Europe (Fig. 1, lower right).
Figure 1: Anomalies of 2-metre temperature (left) and total precipitation (right) over Europe in June 1976 (top) and June 2025 (bottom), from ERA-5 reanalysis data. Anomalies are relative to the period 1990—2020. Plots generated at https://climatereanalyzer.org/
Spring
Looking back a few months to spring, we see a very different picture this year compared to 1976. The spring of 1976 was actually colder than average in Europe (Fig. 2, top left; although note that in the climate of the 1970s these were actually roughly average temperatures). In contrast, in spring 2025 positive temperature anomalies can be seen over almost the whole of Europe (Fig. 2, lower left), and in fact looking more broadly (not shown), these positive temperature anomalies occurred over almost all northern hemisphere land. For the British Isles, spring 2025 was the warmest on record, and the second warmest on record for Europe. Looking at precipitation, the dry anomalies in spring 1976 were centred over France, and actually the UK had a fairly average amount of spring rainfall (Fig. 2, upper right). In contrast, in 2025 the dry anomalies were centred over the UK (Fig. 2, lower right), and the British Isles experienced one of the driest springs on record. Another notable feature is the wet anomalies over Southern Europe. Most of this rain occurred in March, when a series of intense storms caused devastating floods in Spain.
Figure 2: Anomalies of 2-metre temperature (left) and total precipitation (right) over Europe in spring (MAM) 1976 (top) and spring 2025 (bottom), from ERA-5 reanalysis data. Anomalies are relative to the period 1990—2020. Plots generated at https://climatereanalyzer.org/
Drought conditions over different timescales
What made summer 1976 so exceptional was the severe drought conditions in the UK. These were driven by the previous two winters being dry, and also the previous summer being hot and dry, and this prolonged dry period had a large impact on not only rivers and reservoirs, but also groundwater reserves which build up over longer periods (Baker et al, 2019 ). Drought indices calculated over different periods can illustrate these impacts. The 6-month Standardised Precipitation Index (SPI) for June (based on precipitation accumulated over the period January-June) shows that in 1976 the “extremely dry” area covered only the southern half of the UK. In contrast, the 6-month SPI for June 2025 shows the “extremely dry” areas extending over most of the east of the UK, with most other areas at least “moderately dry”. However, looking at the 18-month SPI, the drought in 1976 was more extensive, with all except the very north-west under dry conditions, and much of England and Northern Ireland experiencing “extremely dry” conditions. The 18-month SPI for June 2025 shows that the dry areas are mainly in Scotland and Northern Ireland, and no areas in the “extremely dry” category. Further south, where many of the UK’s groundwater aquifers are, the 18-month SPI is near normal. While this year there have now been hosepipe bans announced in three areas of England, the restrictions in public water supply were much more extreme in 1976. In some areas, water supply to individual houses were switched off and replaced by standpipes in the streets, and in other areas the water supply was restricted to certain parts of the day. These kind of extreme measures seem unlikely for this year – although it is uncertain how long the dry conditions will continue.
Figure 3: 6-month (left panels) and 18-month (right panels) standardised precipitation index (SPI) for June 1976 (top) and June 2025 (bottom). Plots generated at the UKCEH UK water resources portal: https://ukwrp.ceh.ac.uk/
Outlook
How will the rest of summer 2025 pan out? At the time of writing, the next couple of weeks look likely to be more changeable for the UK, with some cooler temperatures and much needed rain likely. However, longer-range forecasts for August show a higher than normal chance of continued dominance of high pressure and hot, dry conditions over the UK and much of mainland Europe.
Reference
Baker, L., Shaffrey, L. & Hawkins, E. (2021). Has the risk of a 1976 north-west European summer drought and heatwave event increased since the 1970s because of climate change?. Q J R Meteorol Soc, 147(741), 4143–4162. https://doi.org/10.1002/qj.4172