nomadseason

September Weather in Eureka, United States

Last updated: June 24, 2025

In September, the average temperature in Eureka, United States is a pleasant 21°C (70°F), with temperatures fluctuating between a cool 5°C (41°F) and a warm 35°C (95°F). Expect about 69 mm (2.7 in) of precipitation spread over 8 days, contributing to an average humidity level of 80%.

September Temperature in Eureka

In September in Eureka, the average temperature is 21°C (70°F). Maximums can reach 35°C (95°F), while minimums can drop to 5°C (41°F). This variability in temperature makes it essential for travelers to pack both lightweight clothing for the warm days and warmer layers for the cooler evenings.

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

The chart illustrates September temperature patterns in Eureka, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Eureka, September typically has an average temperature of 21°C (70°F), with highs reaching up to 35°C (95°F) and lows dropping to around 5°C (41°F).
JanFebMarAprMayJunJulAugSepOctNovDec272941516474777470564034
Data source: Temperature data for Eureka generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Eureka

In Eureka in September, the precipitation amount is 69 mm (2.7 in) that falls over a period of 8 days.

September Precipitation Trends in Eureka

The chart displays monthly precipitation patterns in Eureka, 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 Eureka, September typically receives around 69 mm (2.7 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec616810611716513810980691305655
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Eureka

In Eureka in September humidity is 80%. With an average temperature of 21°C (70°F), this humidity feels like a warm, enveloping blanket that can make even short walks feel draining, urging travelers to seek shade or a cool drink frequently.

September Average Humidity in Eureka

This chart illustrates the average monthly humidity levels in Eureka, 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 Eureka is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%83%84%85%79%82%80%81%80%82%88%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Eureka

In Eureka 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 Eureka.

Maximum UV Index Levels in Eureka for September

The chart shows the monthly maximum UV Index (UVI) for Eureka 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 Eureka typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec357810111098642
Data source: Eureka 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 Eureka Compares to Other Months

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

This table compares monthly weather conditions in Eureka, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (27°F)61 mm (2.4 inches)82%moderate
February Weather-2°C (29°F)68 mm (2.7 inches)83%moderate
March Weather5°C (42°F)106 mm (4.2 inches)84%high
April Weather10°C (51°F)117 mm (4.6 inches)85%very high
May Weather18°C (64°F)165 mm (6.5 inches)79%very high
June Weather23°C (74°F)138 mm (5.4 inches)82%extreme
July Weather25°C (77°F)109 mm (4.3 inches)80%very high
August Weather23°C (74°F)80 mm (3.1 inches)81%very high
September Weather21°C (70°F)69 mm (2.7 inches)80%very high
October Weather13°C (56°F)130 mm (5.1 inches)82%high
November Weather4°C (40°F)56 mm (2.2 inches)88%moderate
December Weather1°C (34°F)55 mm (2.2 inches)84%low

Compare Eureka's Climate with Cities Worldwide