Helsinki
Finland
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Helsinki, Finland

A scenic reflection in the water of the illuminated city of Helsinki in Finland, viewed from the water
A scenic reflection in the water of the illuminated city of Helsinki in Finland, viewed from the water
September, the first month of the autumn, in Helsinki, is also a moderate month, with temperature in the range of an average low of 8.7°C (47.7°F) and an average high of 14.6°C (58.3°F).

Temperature

In Helsinki, the average high-temperature in September decreases, from an enjoyable 19.8°C (67.6°F) in August, to a moderate 14.6°C (58.3°F). In September, the average low-temperature is 8.7°C (47.7°F).

Rainfall

In September, in Helsinki, the rain falls for 14 days. Throughout September, 56mm (2.2") of precipitation is accumulated. In Helsinki, during the entire year, the rain falls for 182 days and collects up to 655mm (25.8") of precipitation.

Snowfall

In Helsinki, Finland, during the entire year, snow aggregates up to 740mm (29.1").

Sea temperature

In Helsinki, Finland, the average seawater temperature is 14°C (57.2°F). Swimming in 14°C (57.2°F) is considered life-threatening. Even a few minutes in 13°C (55.4°F) water is uncomfortable, and swimming below 10°C (50°F) may cause total loss of breathing control and cold shock, depending on a person's physique.

Daylight

In Helsinki, the average length of the day in September is 12.9h.

Sunshine

In September, the average sunshine is 5h.

UV index

The average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to the UV radiation for average individuals.
In September, the average maximum UV index of 3 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.

What is the temperature in September in Helsinki?

In Helsinki, in September, the average high-temperature is 14.6°C (58.3°F), and the average low-temperature is 8.7°C (47.7°F).

How many days does it rain in September in Helsinki?

In Helsinki, Finland, in September, it is raining for 14 days, with typically 56mm (2.2") of accumulated precipitation.

How cold is the water in September in Helsinki?

In September, the average sea temperature in Helsinki is 14°C (57.2°F). Swimming in 14°C (57.2°F) is considered life-threatening. Even a few minutes in 13°C (55.4°F) water is uncomfortable, and swimming below 10°C (50°F) may cause total loss of breathing control and cold shock, depending on a person's physique.

What is the average length of the day in September in Helsinki?

In September, the average length of the day in Helsinki, Finland, is 12.9h.

How many hours of sunshine does Helsinki have in September?

The average sunshine in September in Helsinki is 5h.

What is the UV index reading in September in Helsinki?

In September, the average daily maximum UV index in Helsinki, Finland, is 3. A UV Index estimate of 3 to 5 represents a moderate health threat from unprotected exposure to the UV radiation.
Average temperature in September - Helsinki, Finland
  • Average high temperature in September: 14.6°C

The warmest month (with the highest average high temperature) is July (21.5°C).
The month with the lowest average high temperature is February (-1.9°C).

  • Average low temperature in September: 8.7°C

The month with the highest average low temperature is July (14.2°C).
The coldest month (with the lowest average low temperature) is February (-7.4°C).

Average rainfall in September - Helsinki, Finland
  • Average rainfall in September: 56mm

The wettest month (with the highest rainfall) is August (80mm).
The driest month (with the lowest rainfall) is April (32mm).

Average rainfall days in September - Helsinki, Finland
  • Average rainfall days in September: 14 days

The month with the highest number of rainy days is December (20 days).
Months with the lowest number of rainy days are April and May (11 days).

Average snowfall in September - Helsinki, Finland
  • Average snowfall in September: 0mm

The month with the highest snowfall is February (230mm).
Months with the lowest snowfall are April, May, June, July, August, September and October (0mm).

Average sea temperature in September - Helsinki, Finland
  • Average sea temperature in September: 14°C

The best month for swimming (with the highest average sea temperature) is August (16°C).
Coldest months (with the lowest average sea temperature) are February and March (1°C).

Average daylight in September / Average sunshine in September - Helsinki, Finland
  • Average daylight in September: 12.9h

The month with the longest days is June (Average daylight: 18.8h).
The month with shortest days is December (Average daylight: 6h).

  • Average sunshine in September: 5h

The month with most sunshine is June (Average sunshine: 9.9h).
The month with least sunshine is December (Average sunshine: 0.9h).

Average UV index in September - Helsinki, Finland
  • Average UV index in September: 3

Months with the highest UV index are June and July (UV index 5).
Months with the lowest UV index are January, February, November and December (UV index 0).