Weather in Kostroma for the month
The full September calendar: model forecast through September 25, then the long-term climate normal.
🔮 What September will be like
📅 September calendar2-week forecast →
🌅 September astronomy
🌊 Water in September
📒 Weather diary in Kostroma
Ready-made observation table for September: past days are already filled in with weather-station data — for school and beyond. Open the diary →
✉️ Weather forecast by email
Get the forecast for this city by email — every day at 17:00 Moscow time.
FAQ about weather in Kostroma ❓
What will the weather be like in September in Kostroma?
The forecast part of September is near normal: +8°…+21° by day, no prolonged rain. The second half is shown from the climate normal: on average +16° by day and +9° at night.
When are the best weekend days of September?
The forecast points to 20 September: +20°. Models don’t see beyond two weeks — check back, the page updates daily.
How accurate is a monthly forecast?
Honestly: models are reliable up to ~14 days. So through September 25 we show the model forecast, and beyond that — each day’s climate normal from long-term observations (ERA5). It is a statistical expectation, not a guarantee.
Weather in Kostroma — in detail
Weather forecast in Kostroma for the month: from +6° to +21° day and night. Warmest day — Tuesday, September 22 (up to +21°). Coolest — Wednesday, September 16 (+6°). No significant precipitation. Trend: it cools toward the end. See also the forecast for 2 weeks and the weather archive.
To quickly check the weather in Kostroma anytime, add the city to favorites — and get a daily forecast by email at 17:00 (Moscow time). Note: the forecast may be refined as new data arrives. Data: OpenWeather, Open-Meteo, met.no.