Weather and climate in Helsinki (Finland)

The climate of Helsinki is Baltic, that is, moderately continental, with cold winters, during which the average temperature is a few degrees below freezing, and mild to pleasantly warm summers.
The city, the capital of Finland, is located on the southern coast, at the 60th parallel.
On December 22nd, the sun rises at 9:25 and sets at 14:15. Instead, the white nights, when it doesn't get completely dark even at midnight, occur from 12 May to 2 August.
In winter, there can be cold spells of arctic origin. During these periods, the sea can freeze, though less often than in the Gulf of Bothnia. At Malmi airport, the coldest record is -35.3 °C (-31.5 °F) and was set in January 1987.
In a year, there are 130 days with temperatures below freezing. Generally, snow covers the ground from December 10 to April 10, with a maximum of 20/25 cm (8/10 in) from late February to mid-March. However, the winter of 2019-2020 was exceptionally mild, and for the first time there was almost always no snow on the ground.
In summer, on the hottest days of the year, the temperature generally reaches 28/30 °C (82/86 °F). On average, only 12 days a year with highs above 25 °C (77 °F) are recorded. The highest record is 33.2 °C (91.8 °F) and was set in July 2019.

Best Time

The best time to visit Helsinki is the summer, from June to August, since it is the mildest season. However, you must take into account some rainy days and a bit of cold at night.

Helsinki - Climate data

The average temperature of the coldest month (February) is of -4.3 °C (24.3 °F), that of the warmest month (July) is of 18 °C (64.4 °F). Here are the average temperatures.
Precipitation amounts to 675 millimeters (26.6 inches) per year: so, it is at an intermediate level. It ranges from 35 mm (1.4 in) in the driest months (March, April, May) to 80 mm (3.1 in) in the wettest one (August). Here is the average precipitation.
The sea temperature ranges from 1 °C (34 °F) in February, March to 17 °C (63 °F) in August. Here are the average sea temperatures.
There are on average around 1780 sunshine hours per year. Here are the average hours of sunshine per day.

Helsinki - Weather by month

Based on the period 1991-2020

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January is generally a very cold month. The average temperature is of -3.8 °C (25 °F), with a minimum of -6.4 °C (20.5 °F) and a maximum of -1.1 °C (29.9 °F).
On the coldest nights of the month, the temperature usually drops to around -19.5 °C (-3 °F). However, it dropped to -31 °C (-23.8 °F) in January 2003.
On the warmest days of the month, the temperature usually reaches around 4.5 °C (40 °F). However, it reached 8.4 °C (47.1 °F) in January 2007.
Precipitation amounts to 60 mm (2.4 in), distributed over 12 days.
The day lasts on average 6 hours and 50 minutes. So the days are short.
There is an average of 1 hour of sunshine per day. So, the sun shines 18% of the time.
The average humidity is 88%. Hence, the air is normally humid.
The average wind speed is 12 kph (7 mph).
The average sea temperature is of 2 °C (35.5 °F). Therefore, the sea is very cold for swimming.

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February, the coldest month of the year, is generally a very cold month. The average temperature is of -4.3 °C (24 °F), with a minimum of -7.1 °C (19.3 °F) and a maximum of -1.5 °C (29.2 °F).
On the coldest nights of the month, the temperature usually drops to around -18.5 °C (-1.5 °F). However, it dropped to -29.6 °C (-21.3 °F) in February 1999.
On the warmest days of the month, the temperature usually reaches around 4.5 °C (40 °F). However, it reached 10.3 °C (50.5 °F) in February 1998.
Precipitation amounts to 45 mm (1.8 in), distributed over 9 days.
The day lasts on average 9 hours and 10 minutes.
There are on average 2.5 hours of sunshine per day. So, the sun shines 29% of the time.
The average humidity is 86%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).
The average sea temperature is of 1 °C (34 °F). Therefore, the sea is very cold for swimming.

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March is generally a very cold month. The average temperature is of -1.0 °C (30 °F), with a minimum of -4.3 °C (24.2 °F) and a maximum of 2.3 °C (36.1 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -13.5 °C (7.5 °F). However, it dropped to -23.4 °C (-10.1 °F) in March 2018.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 9 °C (48 °F). However, it reached 16.1 °C (61 °F) in March 2007.
Precipitation amounts to 35 mm (1.4 in), distributed over 8 days.
The day lasts on average 11 hours and 55 minutes.
There are on average 4 hours of sunshine per day. So, the sun shines 35% of the time.
The average humidity is 77%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).
The average sea temperature is of 1 °C (34 °F). Therefore, the sea is very cold for swimming.

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April is generally a quite cold month. The average temperature is of 4.5 °C (40 °F), with a minimum of 0.4 °C (32.8 °F) and a maximum of 8.5 °C (47.4 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -5.5 °C (22 °F). However, it dropped to -11.3 °C (11.7 °F) in April 2018.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 17 °C (62.5 °F). However, it reached 22.7 °C (72.9 °F) in April 2000.
Precipitation amounts to 35 mm (1.4 in), distributed over 7 days.
The day lasts on average 14 hours and 40 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 45% of the time.
The average humidity is 68%.
The average wind speed is 11 kph (7 mph).
The average sea temperature is of 2 °C (35.5 °F). Therefore, the sea is very cold for swimming.

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May is generally a mild month. The average temperature is of 10.4 °C (51 °F), with a minimum of 5.6 °C (42.1 °F) and a maximum of 15.1 °C (59.2 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -0.5 °C (31 °F). However, it dropped to -6.3 °C (20.7 °F) in May 1999.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 23.5 °C (74 °F). However, it reached 28.3 °C (82.9 °F) in May 2018.
Precipitation amounts to 35 mm (1.4 in), distributed over 7 days.
The day lasts on average 17 hours and 20 minutes. So the days are very long.
There are on average 9 hours of sunshine per day. So, the sun shines 51% of the time.
The average humidity is 63%.
The average wind speed is 12 kph (8 mph).
The average sea temperature is of 5 °C (41 °F). Therefore, the sea is very cold for swimming.

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June is generally a very mild month. The average temperature is of 14.9 °C (59 °F), with a minimum of 10.4 °C (50.8 °F) and a maximum of 19.3 °C (66.8 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 4.5 °C (40 °F). However, it dropped to -0.4 °C (31.3 °F) in June 2001.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 25.5 °C (78 °F). However, it reached 30.4 °C (86.7 °F) in June 2011.
Precipitation amounts to 60 mm (2.4 in), distributed over 9 days.
The day lasts on average 18 hours and 50 minutes. So the days are very long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
There are on average 9 hours of sunshine per day. So, the sun shines 47% of the time.
The average humidity is 67%.
The average wind speed is 12 kph (7 mph).
The average sea temperature is of 9 °C (48 °F). Therefore, the sea is very cold for swimming.

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July, the warmest month of the year, is generally a very mild month. The average temperature is of 18 °C (64 °F), with a minimum of 13.7 °C (56.6 °F) and a maximum of 22.3 °C (72.2 °F).
On the coldest nights of the month, the temperature usually drops to around 9 °C (48 °F). However, it dropped to 4.5 °C (40.1 °F) in July 2019.
On the warmest days of the month, the temperature usually reaches around 27.5 °C (82 °F). However, it reached 33.2 °C (91.8 °F) in July 2019.
Precipitation amounts to 55 mm (2.2 in), distributed over 7 days.
The day lasts on average 17 hours and 55 minutes. So the days are very long.
There are on average 9.5 hours of sunshine per day. So, the sun shines 52% of the time.
The average humidity is 70%.
The average wind speed is 11 kph (7 mph).
The average sea temperature is of 15 °C (59 °F). Therefore, the sea is cold for swimming.

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August is generally a very mild month. The average temperature is of 16.7 °C (62 °F), with a minimum of 12.5 °C (54.5 °F) and a maximum of 20.8 °C (69.5 °F).
On the coldest nights of the month, the temperature usually drops to around 6.5 °C (43.5 °F). However, it dropped to 2.3 °C (36.1 °F) in August 1999.
On the warmest days of the month, the temperature usually reaches around 26 °C (79 °F). However, it reached 30.7 °C (87.3 °F) in August 2018.
Precipitation amounts to 80 mm (3.1 in), distributed over 10 days.
The day lasts on average 15 hours and 30 minutes. So the days are long.
There are on average 7 hours of sunshine per day. So, the sun shines 46% of the time.
The average humidity is 75%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).
The average sea temperature is of 17 °C (62.5 °F). Therefore, the sea is cold for swimming.

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September is generally a mild month. The average temperature is of 12.0 °C (54 °F), with a minimum of 8.3 °C (47 °F) and a maximum of 15.6 °C (60.1 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 0.5 °C (33 °F). However, it dropped to -5 °C (23 °F) in September 2001.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 21 °C (70 °F). However, it reached 24.5 °C (76.1 °F) in September 1991.
Precipitation amounts to 55 mm (2.2 in), distributed over 9 days.
The day lasts on average 12 hours and 50 minutes.
There are on average 5 hours of sunshine per day. So, the sun shines 37% of the time.
The average humidity is 80%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).
The average sea temperature is of 14 °C (57 °F). Therefore, the sea is very cold for swimming.

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October is generally a quite cold month. The average temperature is of 6.2 °C (43 °F), with a minimum of 3.5 °C (38.2 °F) and a maximum of 9 °C (48.2 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -5 °C (22.5 °F). However, it dropped to -15.3 °C (4.5 °F) in October 2002.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 15 °C (58.5 °F). However, it reached 19.8 °C (67.6 °F) in October 2001.
Precipitation amounts to 75 mm (3 in), distributed over 10 days.
The day lasts on average 10 hours and 0 minutes.
There are on average 2.5 hours of sunshine per day. So, the sun shines 27% of the time.
The average humidity is 84%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).
The average sea temperature is of 10 °C (50 °F). Therefore, the sea is very cold for swimming.

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November is generally a cold month. The average temperature is of 1.8 °C (35 °F), with a minimum of -0.4 °C (31.4 °F) and a maximum of 4 °C (39.2 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -9 °C (15.5 °F). However, it dropped to -17.5 °C (0.5 °F) in November 1998.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 9.5 °C (49 °F). However, it reached 14.1 °C (57.4 °F) in November 1999.
Precipitation amounts to 75 mm (3 in), distributed over 12 days.
The day lasts on average 7 hours and 25 minutes. So the days are short.
There is an average of 1 hour of sunshine per day. So, the sun shines 17% of the time.
The average humidity is 88%. Hence, the air is normally humid.
The average wind speed is 12 kph (7 mph).
The average sea temperature is of 7 °C (44.5 °F). Therefore, the sea is very cold for swimming.

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December is generally a very cold month. The average temperature is of -1.3 °C (30 °F), with a minimum of -3.7 °C (25.4 °F) and a maximum of 1 °C (33.8 °F).
On the coldest nights of the month, the temperature usually drops to around -14.5 °C (6 °F). However, it dropped to -25.4 °C (-13.7 °F) in December 2001.
On the warmest days of the month, the temperature usually reaches around 5.5 °C (42.5 °F). However, it reached 10.3 °C (50.5 °F) in December 2015.
Precipitation amounts to 65 mm (2.6 in), distributed over 12 days.
The day lasts on average 6 hours and 0 minutes. So the days are short. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There is an average of 1 hour of sunshine per day. So, the sun shines 14% of the time.
The average humidity is 88%. Hence, the air is normally humid.
The average wind speed is 13 kph (8 mph).
The average sea temperature is of 3 °C (37.5 °F). Therefore, the sea is very cold for swimming.