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September Weather in Lammi, Finland

Last updated: August 23, 2025

In Lammi, Finland, the average temperature for September hovers around 11°C (52°F). Expect a chill in the air, with minimums possibly dipping to -2°C (29°F), while the mercury can rise to a pleasant 23°C (74°F). Be prepared for 67 mm (2.6 in) of precipitation spread over 12 days, and remember to dress for the moisture—average humidity is a notable 90%!

September Temperature in Lammi

In September in Lammi, the average temperature is 11°C (52°F). The maximum can reach 23°C (74°F) and the minimum can be as low as -2°C (29°F). Be sure to pack layers to stay comfortable during your travels!

September Weather in Lammi: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Lammi, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Lammi, September typically has an average temperature of 11°C (52°F), with highs reaching up to 23°C (74°F) and lows dropping to around -2°C (29°F).
JanFebMarAprMayJunJulAugSepOctNovDec252329385061636052433628
Data source: Temperature data for Lammi generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Lammi

In Lammi in September, the precipitation amount is 67 mm (2.6 in) distributed over 12 days.

September Precipitation Trends in Lammi

The chart displays monthly precipitation patterns in Lammi, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Lammi, September typically receives around 67 mm (2.6 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec484244475869838267785367
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Lammi

In Lammi in September, humidity is 90%. With an average temperature of 11°C (52°F), this humidity feels like a heavy blanket that clings to your skin, making travel uncomfortable and muggy.

September Average Humidity in Lammi

This chart illustrates the average monthly humidity levels in Lammi, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Lammi is approximately 90%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec97%95%93%87%75%75%80%83%90%93%94%95%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Lammi

In Lammi in September, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Lammi, you can check the information here.

Maximum UV Index Levels in Lammi for September

The chart shows the monthly maximum UV Index (UVI) for Lammi in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Lammi typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec113456653211
Data source: Lammi September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Lammi Compares to Other Months

Weather in Lammi varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Lammi, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Lammi, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-4°C (25°F)48 mm (1.9 inches)97%low
February Weather-5°C (24°F)42 mm (1.7 inches)95%low
March Weather-2°C (29°F)44 mm (1.7 inches)93%moderate
April Weather3°C (38°F)47 mm (1.8 inches)86%moderate
May Weather10°C (50°F)58 mm (2.3 inches)75%moderate
June Weather16°C (61°F)69 mm (2.7 inches)75%high
July Weather17°C (63°F)83 mm (3.3 inches)80%high
August Weather16°C (61°F)81 mm (3.2 inches)83%moderate
September Weather11°C (52°F)67 mm (2.6 inches)90%moderate
October Weather6°C (43°F)78 mm (3.1 inches)93%low
November Weather2°C (36°F)53 mm (2.1 inches)94%low
December Weather-2°C (28°F)67 mm (2.6 inches)95%low

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