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September Weather in Somerville, United States

Last updated: June 24, 2025

The average temperature in Somerville, United States during September is a pleasant 24°C (76°F). Be prepared for temperature fluctuations, as it can dip to a chilly 10°C (50°F) or soar to a scorching 36°C (96°F). Expect 114 mm (4.5 in) of precipitation spread over 7 days, with the average humidity hovering around 70%.

September Temperature in Somerville

In September in Somerville, the average temperature is 24°C (76°F), with maximums reaching 36°C (96°F) and minimums dropping to as low as 10°C (50°F). This climate makes Somerville an ideal destination for travelers seeking warm weather while allowing for comfortable evenings.

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

The chart illustrates September temperature patterns in Somerville, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Somerville, September typically has an average temperature of 24°C (76°F), with highs reaching up to 36°C (96°F) and lows dropping to around 10°C (50°F).
JanFebMarAprMayJunJulAugSepOctNovDec424655617178817975645047
Data source: Temperature data for Somerville 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 Somerville

In Somerville in September, the total precipitation amount is 114 mm (4.5 in) over the course of 7 days.

September Precipitation Trends in Somerville

The chart displays monthly precipitation patterns in Somerville, 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 Somerville, September typically receives around 114 mm (4.5 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec10017216513510510912511411510575145
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Somerville

In Somerville in September, humidity is 70%. With an average temperature of 24°C (76°F), this humidity feels like a warm, enveloping blanket that can make outdoor activities feel a bit sticky and heavier, so travelers should stay hydrated and take regular breaks to enjoy the sights comfortably.

September Average Humidity in Somerville

This chart illustrates the average monthly humidity levels in Somerville, 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 Somerville is approximately 70%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%85%84%81%83%83%80%74%70%73%85%88%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Somerville

In Somerville in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Somerville.

Maximum UV Index Levels in Somerville for September

The chart shows the monthly maximum UV Index (UVI) for Somerville 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 Somerville typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46810111111109753
Data source: Somerville 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 Somerville Compares to Other Months

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

This table compares monthly weather conditions in Somerville, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (42°F)100 mm (4.0 inches)86%moderate
February Weather8°C (46°F)172 mm (6.8 inches)85%high
March Weather13°C (55°F)165 mm (6.5 inches)84%very high
April Weather16°C (61°F)135 mm (5.3 inches)81%very high
May Weather22°C (72°F)105 mm (4.1 inches)83%extreme
June Weather26°C (78°F)109 mm (4.3 inches)83%extreme
July Weather27°C (81°F)124 mm (4.9 inches)80%extreme
August Weather26°C (79°F)114 mm (4.5 inches)73%very high
September Weather24°C (76°F)114 mm (4.5 inches)70%very high
October Weather18°C (65°F)105 mm (4.1 inches)73%high
November Weather10°C (51°F)75 mm (2.9 inches)85%moderate
December Weather8°C (47°F)145 mm (5.7 inches)88%moderate

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