The average maximum temperature from June to August is around . Due to the sea effect, especially on hot summer days, daytime temperatures are slightly cooler and nighttime temperatures higher than further inland. The highest temperature recorded in the city was on 28 July 2019 at the Kaisaniemi weather station, breaking the previous record of set in July 1945 at the Ilmala weather station. The lowest temperature recorded in the city was on 10 January 1987, although an unofficial low of was recorded in December 1876. Helsinki Airport (in Vantaa, 17 km north of Helsinki city centre) recorded a maximum temperature of on 29 July 2010 and a minimum of on 9 January 1987. Precipitation comes from frontal passages and thunderstorms. Thunderstorms are most common in summer.
The average maximum temperature from June to August is around . Due to the sea effect especially on hot summer days, daytime temperatures are slightly cooler and nighttime temperatures higher than further inland. The highest temperature recorded in the city was on 28 July 2019 at the Kaisaniemi weather station, breaking the previous record of set in July 1945 at the Ilmala weather station. The lowest temperature recorded in the city was on 10 January 1987, although an unofficial low of was recorded in December 1876. Helsinki Airport (in Vantaa, 17 km, north of Helsinki city centre) recorded a maximum temperature of on 29 July 2010 and a minimum of on 9 January 1987. Precipitation comes from frontal passages and thunderstorms. Thunderstorms are most common in summer.