According to the Finnish Meteorological Institute, May was unusually, in many places even exceptionally, warm. The anomalies were particularly great in Lapland.
Photo: Tero Sivula
The mean temperature for May ranged from slightly over 13° C in inland Southern and Central Finland to about 7° C in northernmost Lapland. Seen against the long-term average, May was clearly warmer than usual throughout Finland. The difference was greater in the north than in the south.
The Finnish Meteorological Institute’s statistics show that the difference was over 4 degrees in northernmost Lapland and from 2 to 3 degrees in Southern and Western Finland. The highest temperature for the month was 30.5° C, measured in Utsjoki Kevo, on 31 May. The lowest temperature for the month, –9.7° C, was also measured at the same station, on 2 May.
The last days of the month were particularly warm in Northern Finland, where temperature records for May were broken at several observation stations. Hot days (over 25° C) numbered nine in May, or the same as three years ago. During the measurement history, which started in 1961, the highest number of hot days for May was recorded in 1984, when they numbered 13. The statistical average for hot days in May is three.
New mean temperature records were also reached at several observation stations. A very warm month of May occurred previously in 2010. Other warm months of May have been recorded, for instance, in 1963, 1984 and 1993. Thermal summer began clearly earlier than normally in the whole of Finland: on 7 May in Southern Finland and on 17 May in Northern Lapland. Especially in Lapland, the difference from the long-term average was considerable: in Northern Lapland as much as over a month.
In most of the country, monthly precipitation was less than normally, in some places well below half of the usual figure. The most abundant rains were measured in some locations on the southern and western coasts, in Central Finland and in Northern Lapland, where normal readings were reached in some places. Among the observation stations, the most rain was measured in Nurmes, where the reading was 63 millimetres. The least rain, or 7 millimetres, was measured in Virolahti. The greatest daily precipitation, 29.7 millimetres, was measured in Tohmajärvi on 9 May. At the beginning of the month, the snow depth in some locations of Central and Northern Lapland was over 50 centimetres, but all of the snow had disappeared in Finland by 24 May. The number of ground flashes registered during the month was about 6,000. This is about 2,500 fewer than the average for May.
Despite the warm May, the mean temperature for the spring months, or March–May, fell below average in almost all of Finland. The reason was the unusually cold March. Temperatures were slightly warmer than average only in some places of northernmost Lapland. The mean temperature ranged from slightly over +2° C in Southern Finland to just under -3° C in Enontekiö, Lapland. In Southern Finland, thermal spring began in early April, which is a little over a week later than usual. In Northern Lapland, thermal spring began in mid-April, or about half a month earlier than usual. Because of the early onset of thermal summer, thermal spring was unusually short. The thermal growing season began in Southern Finland around 20 April, or slightly earlier than normally. In Northern Lapland, the thermal growing season began in mid-May, or about two weeks earlier than normally.
Precipitation for the spring was below average for almost all of Finland. Precipitation was above average only in coastal areas between Pori and Vaasa, and in Kainuu. The least rain was measured in Southeastern Finland and in Southern and Northwestern Lapland, where the figures were less than 60 per cent of the normal precipitation.
Weather statistics from the Climate Service, tel. 0600 1 0601 (€ 4.01/min. + local network charge)
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Weather statistics for May (in Finnish): http://ilmatieteenlaitos.fi/toukokuu
The Finnish Meteorological Institute’s weather application for iPhone and Android phones: