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October Weather in Boulder, United States

Last updated: June 24, 2025

In October, the average temperature in Boulder, United States hovers around 3°C (38°F). Temperatures can swing dramatically, with minimums dipping to -26°C (-14°F) and maximums soaring to 25°C (77°F). Expect about 44 mm (1.7 in) of precipitation over 10 days, while the air remains comfortably humid with an average humidity of 72%.

October Temperature in Boulder

In October in Boulder, the average temperature is 3°C (38°F). Maximum temperatures can reach 25°C (77°F), while minimums can drop as low as -26°C (-14°F). Be prepared for a wide range of temperatures when traveling to Boulder during this month.

October Weather in Boulder: Daily Temperature Highs, Lows, and Averages

The chart illustrates October temperature patterns in Boulder, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Boulder, October typically has an average temperature of 3°C (38°F), with highs reaching up to 25°C (77°F) and lows dropping to around -26°C (-14°F).
JanFebMarAprMayJunJulAugSepOctNovDec181528344657656354382718
Data source: Temperature data for Boulder 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.

October Precipitation in Boulder

In Boulder in October, the total precipitation amount is 44 mm (1.7 in) over the course of 10 days.

October Precipitation Trends in Boulder

The chart displays monthly precipitation patterns in Boulder, with values for each month alongside October’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how October’s conditions compare to those of other months. In Boulder, October typically receives around 44 mm (1.7 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec2356406892112443943443432
Data source: Precipitation data for October generated using information from the Copernicus Climate Change Service.
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October Humidity in Boulder

In Boulder in October, humidity is 72%. With an average temperature of 3°C (38°F), this humidity feels like a damp chill that wraps around you, making outdoor activities less enjoyable and necessitating warm, water-resistant clothing for comfortable traveling.

October Average Humidity in Boulder

This chart illustrates the average monthly humidity levels in Boulder, with October’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In October, average humidity in Boulder is approximately 72%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%88%83%78%76%78%77%71%68%72%84%91%
Data source: Humidity data for October generated using information from the Copernicus Climate Change Service.

October UV Index in Boulder

In Boulder in October, 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 Boulder.

Maximum UV Index Levels in Boulder for October

The chart shows the monthly maximum UV Index (UVI) for Boulder in October, 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 October, the maximum UV index in Boulder typically reaches 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689111098532
Data source: Boulder October 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 October Weather in Boulder Compares to Other Months

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

This table compares monthly weather conditions in Boulder, showing how October’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-8°C (18°F)23 mm (0.9 inches)87%moderate
February Weather-9°C (16°F)55 mm (2.2 inches)88%moderate
March Weather-2°C (28°F)40 mm (1.6 inches)83%high
April Weather1°C (34°F)68 mm (2.7 inches)78%very high
May Weather8°C (46°F)92 mm (3.6 inches)76%very high
June Weather14°C (57°F)112 mm (4.4 inches)78%extreme
July Weather18°C (65°F)44 mm (1.7 inches)77%very high
August Weather17°C (64°F)39 mm (1.5 inches)71%very high
September Weather12°C (54°F)43 mm (1.7 inches)68%very high
October Weather3°C (38°F)44 mm (1.7 inches)72%moderate
November Weather-3°C (28°F)34 mm (1.3 inches)84%moderate
December Weather-8°C (19°F)32 mm (1.3 inches)90%low

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