Helsinki in September
In September, Helsinki averages 15°C (59°F) during the day and 8°C (46°F) at night, with around 13 days of rain (70 mm total).
ShoulderConditions are cool — bring a jacket for evenings. Plan for unsettled weather and bring rain gear.
September in Helsinki is outside the typical sweet spot for sightseeing weather. It can still be a great time to visit if you have specific reasons (festivals, off-season pricing, etc.).
How September compares to the rest of the year in Helsinki
September is in the middle of the year for warmth in Helsinki (5th of 12) and moderately rainy compared to the rest of the year (7th of 12). Daytime temperature runs 6°C above the annual average (9°C). September runs 5°C cooler than August (20°C) and cools 7°C in October (8°C).
September sunrise & sunset in Helsinki
Times shown for Helsinki local time (Europe/Helsinki), calculated for the 15th of September. They shift by a few minutes day to day across the month.
Photography light in Helsinki — September
Golden-hour and blue-hour windows for the 15th of September, in Helsinki's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Helsinki in September
Travel writers usually only tell you when to go. Here's when to book flights and lodging for the best mix of price and availability, based on September's tier (Shoulder) and Helsinki's popularity.
Crowds & pricing — September in Helsinki
Helsinki is in a shoulder season month — fewer crowds, slightly lower prices, and a calmer atmosphere than peak weeks. Most major sights stay open with normal hours, though a handful of seasonal restaurants or boat trips may run reduced schedules. Many regulars consider these months the best time to visit because you trade a small amount of weather reliability for a much more pleasant on-the-ground experience.
Why this tier: comfortable tourism weather
Sun & mosquito risk — September in Helsinki
UV is a clear-sky sea-level estimate — clouds, altitude, and reflective surfaces (snow, water) shift it ±30%. Mosquito risk is climate-derived only; for current disease advisories (dengue, malaria, zika) check the CDC or WHO travel pages before your trip.
Sea temperature in Helsinki — September
Across the year Helsinki's sea swings from -0.2°C (January) to 19.4°C (August) — September sits at 17.5°C.
Helsinki in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | -3°C / 27°F | -7°C / 19°F | 55 mm | 17 | 11 |
| February | -3°C / 27°F | -8°C / 18°F | 40 mm | 15 | 11 |
| March | 1°C / 34°F | -5°C / 23°F | 40 mm | 12 | 7 |
| April | 8°C / 46°F | 0°C / 32°F | 35 mm | 11 | 2 |
| May | 15°C / 59°F | 5°C / 41°F | 40 mm | 11 | 0 |
| June | 19°C / 66°F | 11°C / 52°F | 55 mm | 12 | 0 |
| July | 22°C / 72°F | 14°C / 57°F | 75 mm | 12 | 0 |
| August | 20°C / 68°F | 13°C / 55°F | 80 mm | 13 | 0 |
| September | 15°C / 59°F | 8°C / 46°F | 70 mm | 13 | 0 |
| October | 8°C / 46°F | 3°C / 37°F | 80 mm | 15 | 0 |
| November | 3°C / 37°F | -1°C / 30°F | 70 mm | 16 | 5 |
| December | -1°C / 30°F | -5°C / 23°F | 55 mm | 17 | 9 |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for Helsinki in September →
Frequently asked questions
How hot is Helsinki in September?
In September, Helsinki averages a high of 15°C (59°F) and a low of 8°C (46°F) — generally cool.
Does it rain a lot in Helsinki in September?
September can be fairly wet in Helsinki, with about 13 rainy days on average.
Is September a good time to visit Helsinki?
September is cool. It suits travelers who are comfortable with cool weather; check the month-by-month ranking to compare it against the rest of the year.
What should I pack for Helsinki in September?
Pack a warm jacket and layers, plus a compact umbrella or rain jacket. See the full September packing list for Helsinki for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.