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September Weather in Derry, United States

Last updated: June 24, 2025

In September, the average temperature in Derry, United States hovers around 19°C (66°F), with minimums dipping to 3°C (37°F) and highs reaching up to 32°C (89°F). This month typically sees precipitation of 123 mm (4.8 in) over about 10 days, contributing to an average humidity of 67%, creating a lively, yet comfortable atmosphere.

September Temperature in Derry

In September in Derry, the average temperature is 19°C (66°F). The maximum can reach 32°C (89°F), and the minimum can be as low as 3°C (37°F). This makes Derry an ideal destination for travelers seeking a mix of pleasant warmth and cool evenings.

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

The chart illustrates September temperature patterns in Derry, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Derry, September typically has an average temperature of 19°C (66°F), with highs reaching up to 32°C (89°F) and lows dropping to around 3°C (37°F).
JanFebMarAprMayJunJulAugSepOctNovDec293440506168737165554035
Data source: Temperature data for Derry 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 Derry

In Derry in September, the total precipitation amount is 123 mm (4.8 in) over the course of 10 days.

September Precipitation Trends in Derry

The chart displays monthly precipitation patterns in Derry, 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 Derry, September typically receives around 123 mm (4.8 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec961351181381591541219212311796118
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Derry

In Derry in September humidity is 67%. With an average temperature of 19°C (66°F), this humidity feels like a warm embrace that envelops you as you travel, making each step a little heavier but still comfortable enough to explore the vibrant surroundings.

September Average Humidity in Derry

This chart illustrates the average monthly humidity levels in Derry, 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 Derry is approximately 67%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%90%89%88%80%79%74%64%67%81%89%88%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Derry

In Derry in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Derry.

Maximum UV Index Levels in Derry for September

The chart shows the monthly maximum UV Index (UVI) for Derry 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 Derry typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec357910101098642
Data source: Derry 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 Derry Compares to Other Months

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

This table compares monthly weather conditions in Derry, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (30°F)96 mm (3.8 inches)89%moderate
February Weather1°C (34°F)135 mm (5.3 inches)90%moderate
March Weather4°C (40°F)117 mm (4.6 inches)89%high
April Weather10°C (50°F)137 mm (5.4 inches)88%very high
May Weather16°C (61°F)158 mm (6.2 inches)80%very high
June Weather20°C (68°F)154 mm (6.1 inches)79%very high
July Weather23°C (73°F)121 mm (4.8 inches)74%very high
August Weather22°C (71°F)92 mm (3.6 inches)64%very high
September Weather19°C (66°F)123 mm (4.8 inches)67%very high
October Weather13°C (56°F)116 mm (4.6 inches)81%high
November Weather5°C (41°F)96 mm (3.8 inches)89%moderate
December Weather1°C (35°F)118 mm (4.6 inches)88%low

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