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September Weather in Sejny, Poland

Last updated: August 27, 2025

In September, the average temperature in Sejny, Poland is a pleasant 14°C (57°F). Expect a range from a chilly 0°C (31°F) to a warm 28°C (82°F). During this month, you can anticipate about 70 mm (2.7 in) of precipitation spread over 10 days, contributing to an average humidity of 72%. Prepare for a mix of weather as you enjoy your time in this charming location!

September Temperature in Sejny

In September, in Sejny, the average temperature is 14°C (57°F). Maximum temperatures can reach 28°C (82°F), while minimums can drop to as low as 0°C (31°F). This variable climate makes Sejny a versatile destination for travelers, offering both warm and cool experiences throughout the month.

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

The chart illustrates September temperature patterns in Sejny, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sejny, September typically has an average temperature of 14°C (57°F), with highs reaching up to 28°C (82°F) and lows dropping to around 0°C (31°F).
JanFebMarAprMayJunJulAugSepOctNovDec293036455565666557484032
Data source: Temperature data for Sejny 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 Sejny

In Sejny in September, the precipitation amount is 70 mm (2.7 in) spread over a span of 10 days.

September Precipitation Trends in Sejny

The chart displays monthly precipitation patterns in Sejny, 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 Sejny, September typically receives around 70 mm (2.7 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec413440457051938770613954
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Sejny

In Sejny in September humidity is 72%. With an average temperature of 14°C (57°F), this humidity feels like a damp embrace, making outdoor activities slightly uncomfortable and requiring careful planning to stay hydrated and enjoy your travels.

September Average Humidity in Sejny

This chart illustrates the average monthly humidity levels in Sejny, 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 Sejny is approximately 72%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%91%88%77%59%59%60%60%72%89%91%93%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Sejny

In Sejny in September, the maximum UV index reaches 5, which corresponds to a moderate Exposure Category. Under these conditions, the estimated time to burn is approximately 30 minutes. For more details, you can check the Hourly UV Index in Sejny.

Maximum UV Index Levels in Sejny for September

The chart shows the monthly maximum UV Index (UVI) for Sejny 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 Sejny typically reaches 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec124568765321
Data source: Sejny 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 Sejny Compares to Other Months

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

This table compares monthly weather conditions in Sejny, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)41 mm (1.6 inches)93%low
February Weather-1°C (30°F)34 mm (1.3 inches)90%low
March Weather2°C (36°F)40 mm (1.6 inches)88%moderate
April Weather7°C (45°F)45 mm (1.8 inches)77%moderate
May Weather13°C (55°F)70 mm (2.8 inches)59%high
June Weather18°C (65°F)51 mm (2.0 inches)59%very high
July Weather19°C (66°F)93 mm (3.7 inches)60%high
August Weather18°C (65°F)87 mm (3.4 inches)60%high
September Weather14°C (57°F)70 mm (2.7 inches)72%moderate
October Weather9°C (48°F)61 mm (2.4 inches)88%moderate
November Weather4°C (40°F)39 mm (1.5 inches)91%low
December Weather0°C (32°F)53 mm (2.1 inches)93%low

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