Helsinki Weather in September
Average highs run from 17°C on September 1 to 12°C on September 30, and lows from 13°C to 9°C. Normal precipitation for the month is 63 mm over about 12 wet days.
September day by day
The normal high and low for each date, in °C.
- Normal low
- Normal high
- Reanalysis extreme high
- Reanalysis extreme low
September at a glance
- Average high
- 15°C
- Average low
- 11°C
- Precipitation
- 63 mm
- Reanalysis high
- 22°CSep 2, 2019
- Reanalysis low
- 4°CSep 30, 2013
- Daylight
- 14 h 11 min to 11 h 33 min
- Cloud cover
- 67%
- Humidity
- 83%
- Dew point
- 10°C
- Wind
- 18.0 km/h
Every day of the month
A wet day has at least 1 mm of precipitation in the reanalysis.
| Date | Normal high | Normal low | Reanalysis high | Reanalysis low | Chance wet |
|---|---|---|---|---|---|
| Sep 1 | 17°C | 13°C | 21°C 2019 | 8°C 2003 | 45% |
| Sep 2 | 17°C | 13°C | 22°C 2019 | 7°C 2003 | 44% |
| Sep 3 | 17°C | 13°C | 20°C 2002 | 7°C 2003 | 43% |
| Sep 4 | 16°C | 13°C | 19°C 2002 | 8°C 1993 | 43% |
| Sep 5 | 16°C | 13°C | 20°C 2002 | 7°C 1993 | 42% |
| Sep 6 | 16°C | 13°C | 19°C 2002 | 8°C 1991 | 42% |
| Sep 7 | 16°C | 13°C | 21°C 2018 | 7°C 1991 | 42% |
| Sep 8 | 16°C | 12°C | 21°C 2018 | 8°C 1993 | 42% |
| Sep 9 | 16°C | 12°C | 21°C 2002 | 8°C 2004 | 43% |
| Sep 10 | 15°C | 12°C | 21°C 2019 | 7°C 1993 | 43% |
| Sep 11 | 15°C | 12°C | 18°C 2013 | 8°C 1996 | 43% |
| Sep 12 | 15°C | 12°C | 19°C 2013 | 7°C 2008 | 42% |
| Sep 13 | 15°C | 12°C | 19°C 2002 | 6°C 1993 | 41% |
| Sep 14 | 15°C | 11°C | 18°C 2006 | 5°C 1993 | 40% |
| Sep 15 | 15°C | 11°C | 18°C 2014 | 7°C 2000 | 39% |
| Sep 16 | 14°C | 11°C | 17°C 2020 | 7°C 2008 | 39% |
| Sep 17 | 14°C | 11°C | 17°C 2015 | 7°C 1993 | 39% |
| Sep 18 | 14°C | 11°C | 17°C 2001 | 5°C 1993 | 38% |
| Sep 19 | 14°C | 11°C | 18°C 2018 | 6°C 1993 | 37% |
| Sep 20 | 14°C | 11°C | 18°C 2018 | 5°C 1993 | 36% |
| Sep 21 | 14°C | 10°C | 19°C 2018 | 7°C 2002 | 38% |
| Sep 22 | 13°C | 10°C | 18°C 2018 | 6°C 2014 | 38% |
| Sep 23 | 13°C | 10°C | 17°C 2006 | 5°C 2014 | 38% |
| Sep 24 | 13°C | 10°C | 18°C 2020 | 5°C 2014 | 38% |
| Sep 25 | 13°C | 10°C | 17°C 2020 | 5°C 2013 | 38% |
| Sep 26 | 13°C | 10°C | 17°C 2020 | 5°C 2013 | 38% |
| Sep 27 | 13°C | 10°C | 17°C 2005 | 6°C 1993 | 39% |
| Sep 28 | 12°C | 9°C | 16°C 2006 | 5°C 1993 | 42% |
| Sep 29 | 12°C | 9°C | 15°C 1999 | 5°C 1993 | 43% |
| Sep 30 | 12°C | 9°C | 17°C 2011 | 4°C 2013 | 43% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (GMT+3).
- September 1
- sunrise 6:14 AM, sunset 8:25 PM
- September 30
- sunrise 7:23 AM, sunset 6:56 PM
Other months
Sources
Cloud, humidity, wind and sunshine, and temperature and precipitation: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.