Warmer nights usher in highest May temperatures since records began at Lancaster University

Man taking readings from Lancaster's weather station on sunny day

May 2024 was the warmest since records began at Lancaster University’s Hazelrigg Weather Centre – almost 3°C higher than the long-term average.

Data shows that although the average daytime maximum temperature had been equalled in three previous years since records began in 1966, the overnight minimum had not. Night-time temperatures were disproportionately higher (relative to normal) than the daytime temperatures.

May 2024 also saw the wettest 24-hour period ever recorded for May at Hazelrigg, with 49.1mm of rain falling between 22 and 23 May. Dr James Heath, from Lancaster Environment Centre and part of the team that takes daily weather readings at Hazelrigg, said the discrepancy in relative warmth between day and night is partly due to having a fair amount of cloudy, unsettled conditions.

This would tend to supress the temperatures during the day but also – something we might notice less – prevent them from falling very low overnight. This is reflected in the fact that rainfall was 66% above average, while sunshine was only 75% of average.

“It just shows that with the ongoing rise in global average temperatures, the more likely we are to exceed previous records in any one place or month,” James said. “It doesn’t necessarily have to be wall-to-wall sunshine – though in May, there were several warm sunny periods in between the duller, wetter conditions.

“In fact, here, every month this year has been significantly above the long-term average temperature, particularly in February and March. Even April, which may have often felt chilly, came out significantly warmer than average, both day and night – though like May, more so by night.”

James explained that this doesn’t mean that every month will be warmer than the same month the previous year, as there still a lot of variability.

“In terms of rainfall, given the right atmospheric conditions to produce rain of course, higher temperatures lead to more intense rainfall, as the air can hold more moisture,” he added.

The warmest day in May 2024 was the 11th, at 23.2°C, with an overnight minimum of 15.5°C.

Average temperature for May (1966-present): 11.0 °C (Max 14.7, Min 7.2)

2024: 13.8 °C (Max 17.0, Min 10.6)

2008: 13.25 °C (17.2, 9.3)

2018: 12.8 °C (17.1, 8.5)

2017: 12.8 °C (17.0, 8.6)

1992: 12.7 °C 16.8, 8.6)

Average rainfall for May (1966-present): 65.4 mm

1997: 130.2

1979: 129.3

2015: 126.7

1967: 115.8

2002: 114.34

2024: 108.4 June 2023, was the hottest on record at Hazelrigg, and July 2023 became the wettest July on record at the site.

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