Wales' previous warmest summer was in 1995, when there was a mean temperature of 16.04C [PA Media] Wales has had its hottest summer on record, according to provisional statistics from the Met Office. It beats the previous record which has stood for 30 years. The mean temperature across the country has been confirmed as 16.06C. This is calculated as an average of the overnight low and daytime high temperatures for June, July and August.