WEATHER ANOMALIES IN LATVIA, 2015

The year 2015 average air temperature in Latvia was +7.8ºC (2.1 degrees above the normal for the period of 1961-1990), putting it as the 1st warmest in the long term data row (Fig. 1.).

With an annual precipitation amount of 606 mm (92% of normal) the year 2015 was the 23rd driest in the last 92 years and the 3rd driest in the 21st century (Fig. 2).

For most of the months of 2015 as well as all of the seasons, the average air temperature was above the normal (Fig.3.).

Time period from January to March 2015 was the warmest ever recorded in the corresponding long term data rows (since year 1924), average air temperature was 4.6 to 4.7 degrees above the 1961-1990 normal. In April average air temperature in Latvia was +5.9ºC, with 20 days of April above normal. May, June and October were the only months in 2015 when observed average air temperature was below normal. Beginning of July was warm and in time period from 3 to 5 July the maximum air temperature in some places was above +30ºC and on 2 July new ultraviolet radiation index record (7.9) was set, but the last two 10-day periods in July was below normal and the whole July air temperature was in the range of normal. In early August Latvia was affected by heat wave from 5 to 12 August, the maximum air temperature was recorded on 8 August +35.1ºC in Piedruja (near the Belarusian border). In 2015 December was unusually warm, average air temperature was +2.9ºC which is 5.6ºC above normal, in 9 days at most of meteorological observation stations new daily and 10-day period maximum air temperature records was set.

In 2015 air temperature anomalies were positive for all meteorological stations (Fig. 4) varying from 1.7ºC in Jelgava stations up to 2.4ºC in three stations at once (Dobele, Rujiena and Gulbene).

The amount of precipitation during the year 2015 was variable (Fig. 5).

January 2015 with average precipitation sum in Latvia 78.4 mm was the 3rd wettest in long term data row since 1924, because of relative high air temperatures a lot of precipitation was in form of rain. Also April was relative wet with average precipitation sum of 66.0 mm. August with precipitation sum of 21.3 mm was very dry, it was 7th driest August since 1924, but October with average precipitation sum in Latvia of 8.9 mm was even more drier and it was the driest October month in all historical data row since 1924. Precipitation sum in September was almost corresponding 1961 to 1990 normal, but at night from 7 to 8 September during 12 hours in meteorological observation station Kalnciems (central part of Latvia) the amount of precipitation was 52.2 mm, which is 80% of September normal precipitation amount.

In 2015 annual average wind speed in Latvia was 2.9 m/s and that was the 5th slowest in the long term data row since 1966. The strongest wind during the entire year 2015 was observed on 8 February – the strongest wing gusts was 29.1 m/s in Ventspils station (near the Baltic Sea coast).