Porvoo weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Poor
Best time to visit: July
What is the weather like in Porvoo in September?
In September, Porvoo is cool: daytime highs average 15 °C, and nights cool down to about 10 °C. The sea averages 14.8 °C – swimming is only for the hardy. Expect around 5 hours of sunshine a day. Rain is frequent, with about 10 rainy days and 51 mm in total. All in all, September is not an ideal month for a holiday in Porvoo.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 32 | 18 | 10 |
| Day | 20° | 15° | 8° |
| Night | 14° | 10° | 4° |
| Sea | 18° | 15° | 11° |
| Sun | 8 h | 5 h | 3 h |
| Rain days | 12 | 10 | 11 |
More details for September
- Daylight
- 13 h 1 min06:42 – 19:43
- UV index
- 2 · lowclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 16 km/haverage daily peakAll months
- Cloud cover
- 68 %on averageAll months
- Hot days
- 0 days30 °C or more
- Snow days
- 0 days1 cm or more of fresh snowAll months
- Time zone
- UTC+3Europe/Helsinki
How the score comes together
- Temperatureweight 35 %0 %
- Seaweight 25 %0 %
- Sunshineweight 20 %32 %
- Few rainy daysweight 20 %61 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in September
- A jumper for the evenings
- Rain jacket or umbrella
Porvoo in September: quick answers
Is Porvoo hot in September?
No. In September, Porvoo is cool: daytime highs average 15 °C and nights drop to about 10 °C.
Can you swim in Porvoo in September?
Only if you don't mind cold water: in September the sea averages just 14.8 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Porvoo in September?
Rain is frequent, with about 10 rainy days and 51 mm in total.
Porvoo month by month
The whole year in PorvooAll destinations: FinlandWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences