Expert comment: Wettest July in ºÚ¹Ï³ÔÁÏÍø since 2017
01 August 2023
Dr Stephen Burt, of the Department of Meteorology at the ºÚ¹Ï³ÔÁÏÍø, examines weather data recorded in July 2023.
“July was a cool, wet, dull and rather windy month in ºÚ¹Ï³ÔÁÏÍø, but aside from rainfall, it was far from record-breaking. The perception of a poor month is heightened following as it did a very hot, sunny and dry June, the hottest since 1846 in England.
“The mean temperature for July in ºÚ¹Ï³ÔÁÏÍø was 16.9 °C, slightly below the 30-year (1991-2020) normal of 17.8 °C. The difference was greatest in daytime temperatures, where the mean daily maximum, 21.2 °C, was well below the average 22.7 °C. Owing to predominantly cloudy conditions, nights were often warm, and the mean daily minimum temperature of 12.6 °C was only 0.2 degrees cooler than normal. Overall, it was the coolest July in ºÚ¹Ï³ÔÁÏÍø since 2012, but three Julys including 2012 have been cooler in the past 20 years.
“Only two days reached 25 °C last month. This compares with 14 in June and 17 last July. The hottest day (7th) reached 28.0 °C, almost exactly 10 degrees cooler than last July's record 37.6 °C.
“July was very wet. The month's total rainfall of 92.3 mm was almost twice the normal 49 mm, although there have been two much wetter Julys within the past 20 years (2017 had 123 mm, and 2007 116 mm). The comparison with last July, which received only 3.1 mm and was the driest on the university's long records (which go back to 1908), was striking.
“In terms of sunshine, July was slightly deficient. The month's total of 189 hours at the university site was 7% below the July average of 204 hours and was the dullest since 2017's 177 hours. There have been much duller Julys - in 1965, only 111 hours were recorded at the university.
“July was also rather windy, with fresh or even strong winds on a number of days. The mean wind speed at 0900 GMT being 5.6 knots (6.4 mph), the highest for any July since 2010. On 15 July, winds gusted to near gale force, unusual for a summer month.”