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July Weather in Boulder, United States

Last updated: June 24, 2025

In Boulder, United States, the average temperature in July hovers around 18°C (65°F), offering a pleasant climate. While temperatures can dip to a chilly 0°C (32°F), they can also rise to a warm 34°C (93°F). Expect about 44 mm (1.7 in) of precipitation over 10 days, contributing to an average humidity of 77%. It's a month where you can enjoy a mix of sun and occasional rain!

July Temperature in Boulder

In July in Boulder, the average temperature is 18°C (65°F). Maximums can reach 34°C (93°F), and minimums can be as low as 0°C (32°F). It's wise to prepare for a range of temperatures when traveling to Boulder during this time.

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

The chart illustrates July 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, July typically has an average temperature of 18°C (65°F), with highs reaching up to 34°C (93°F) and lows dropping to around 0°C (32°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.

July Precipitation in Boulder

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

July Precipitation Trends in Boulder

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

In Boulder in July humidity is 77%. With an average temperature of 18°C (65°F), this humidity feels like a warm embrace that's both refreshing and slightly stifling, making it essential for travelers to stay hydrated and take frequent breaks to enjoy the vibrant surroundings without feeling overly fatigued.

July Average Humidity in Boulder

This chart illustrates the average monthly humidity levels in Boulder, with July’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In July, average humidity in Boulder is approximately 77%, 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 July generated using information from the Copernicus Climate Change Service.

July UV Index in Boulder

In Boulder in July, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Boulder.

Maximum UV Index Levels in Boulder for July

The chart shows the monthly maximum UV Index (UVI) for Boulder in July, 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 July, the maximum UV index in Boulder typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689111098532
Data source: Boulder July 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 July 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 July’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 July’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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