The mercury in Northamptonshire thermometers peaked at its lowest August level for almost 30 years last month.
Pitsford School’s monthly weather report says that August 2014’s highest temperature was just 23.9C, reached on Thursday 7.
The school said it was the lowest August maximum temperature since 1986.
The mercury also plunged as low as 6.6C on Thursday, August 21 – the lowest temperature recorded at the weather station since May.
The report added: “August 2014 started off warm with temperatures topping 20C for the first nine days of the month. A high temperature of only 17.6C on the 10th, ended a remarkable run of 32 successive days with temperatures rising to above 20C.
“The arrival of ex-hurricane Bertha then signalled lower temperatures with wind speeds significantly above average.”
The month’s average temperature was 15.5C, below the average of 16.8C – and the first below-average monthly temperature since last November.
The report also said: “Despite the low temperatures, August was still a fairly sunny month with 164.7 hours being recorded, although August last year was significantly more sunny at 207.5 hours.”
August was also a noticeably windy month and there was almost double the average amount of rainfall, the school said.