Heatwave · United Kingdom

The day Britain reached 40 °C

On 19 July 2022 the temperature at RAF Coningsby, in Lincolnshire, reached 40.3 °C: the first time 40 °C had ever been recorded in the United Kingdom. The previous record, 38.7 °C at Cambridge in 2019, was beaten at 46 stations that day. Railways slowed or stopped, a runway at Luton lifted, and grass fires broke out around London, destroying homes in Wennington.

18–19 July 2022 · England · ERA5

Map of the United Kingdom: ERA5 2 m temperature on 19 July 2022 at 15 UTC, above 38 °C over eastern England. — 19 Jul, 15 UTC · 2 m temperature with 500 hPa height. The hottest air over eastern England. ERA5.

40.3°C

Coningsby, 19 July

The UK's highest temperature on record, confirmed by the Met Office.N1

Stations above the old record

Beating the 38.7 °C measured at Cambridge in 2019; some long-running stations by 3–4 °C.N1

39.2°C

ERA5 near Coningsby

The reanalysis comes within about a degree of the record on flat ground.

What happened

Heat had been building over Spain, Portugal and France for a week, with wildfires in the Gironde and temperatures above 45 °C in Portugal. On 17 and 18 July a slow low west of Portugal drew this air north across the Bay of Biscay and the Channel. The Met Office issued its first ever red warning for extreme heat.

18 July set a record for Wales; on 19 July the heat peaked over England. Many stations with a century of records broke them by 3 to 4 °C, an extraordinary margin.N1 The next day a cold front swept the heat away.

A plume from the south

About 1.5 km up, the 850 hPa map shows the plume: a tongue of air above 20 °C, reaching from Iberia across France to southern England, between the low to the west and high pressure to the east.

ERA5 850 hPa temperature with 500 hPa height over Europe, 18 July 2022 12 UTC — 18 Jul, 12 UTC · 850 hPa temperature and 500 hPa height. The plume of hot air from Iberia to Britain. ERA5.

The hottest afternoon

+1.6°C

The margin by which Coningsby's 40.3 °C beat the UK record. Records usually fall by tenths of a degree.

ERA5 2 m temperature over the United Kingdom, 19 July 2022 15 UTC — Afternoon19 Jul, 15 UTC (4 pm local) · 2 m temperature. ERA5.

ERA5 daily mean 2 m temperature over the United Kingdom, 19 July 2022 — Whole day19 Jul · daily mean 2 m temperature: the night was hot too. ERA5.

The grid and the stations

Over the flat land of eastern England the reanalysis comes close to the thermometers: ERA5's afternoon high near Coningsby is 39.2 °C, near London 38.0 °C. In mountains a grid cell can differ from a station by many degrees; here the land is level and the heat was spread over a wide area.

Highest temperature on 19 July 2022, °C
Place	Station	ERA5 grid point
Coningsby	40.3	39.2
London	40.2	38.0

Hourly ERA5 time series in London, 19 July 2022 — London, 19 Jul (UTC) · temperature and dew point, wind and pressure, rain and cloud. ERA5.

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The plumeERA5 · 850 hPa temperature with 500 hPa height · 18 Jul 12 UTC The hottest afternoonERA5 · 2 m temperature · 19 Jul 15 UTC The whole dayERA5 · 2 m temperature · Daily · 19 Jul 2022

References

News

N1Met Office. July heat review. July 2022.The new record, the stations that broke the old one and the margins.