September weather forecast
Colorado, USA

September in Colorado signifies the onset of autumn, with noticeable changes in temperature and the landscape's appearance. Temperatures in areas like the Eastern Plains usually range from 50°F (10°C) to 75°F (23.9°C), showcasing a significant decrease from the summer's peak warmth.

The Front Range cities, including Colorado Springs, start to experience cooler nights and milder days. Meanwhile, the high mountain regions witness the beginning of the fall foliage season, as the aspen trees turn golden, creating a picturesque setting for outdoor exploration.

September brings a reduction in the frequency and intensity of thunderstorms, with precipitation often occurring in the form of light rain. The state's climate becomes less volatile, offering a reprieve from the summer's occasional severe weather patterns.

Snow may make an early appearance in the higher elevations towards the end of the month, hinting at the approaching winter. However, it is typically sporadic and does not impact most of the state's recreational activities.

September's weather embodies the transitional nature of autumn in Colorado, with a gradual cooling of temperatures and the emergence of fall colors. The shift away from the hot, stormy conditions of summer towards the more temperate and stable climate of fall makes this month an attractive time for outdoor pursuits and enjoying Colorado's diverse natural beauty.

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• Denver - September »
  Therefore, Denver's September weather notably moves from the summer heat towards milder, comfortable days of early fall. 
 
 During the shift to September, Denver records a mild decrease in average high-temperature, moving from 83.1°F (28.4°C) in August to a still warm 76.6°F (24.8°C). On the first day of September sunrise is at 6:28 am and sunset at 7:30 pm.
• Colorado Springs - September »
  In Colorado Springs, during September, the rain falls for 10.5 days and regularly aggregates up to 1.3" (33mm) of precipitation. On the last day of September, in Colorado Springs, sunrise is at 6:55 am and sunset at 6:43 pm MDT.
• Aurora - September »
  In Aurora snow does not fall in June through September. September nights in Aurora experience a distinct temperature drop from the daily highs, with an average low-temperature of 53.1°F (11.7°C).
• Fort Collins - September »
  June, August and September, with an average relative humidity of 45%, are the least humid months in Fort Collins. The months with the lowest humidity in Fort Collins are June, August and September, with an average relative humidity of 45%.
• Boulder - September »
  June, August and September, with an average relative humidity of 45%, are the least humid months in Boulder. In Boulder in September, it is raining for 9.9 days, with typically 1.02" (26mm) of accumulated precipitation.
• Pueblo - September »
  On the first day of September in Pueblo sunrise is at 6:28 am and sunset at 7:27 pm. In Pueblo, Colorado, in September, during 7.6 rainfall days, 0.55" (14mm) of precipitation is typically accumulated.
• Greeley - September »
  The months with the lowest humidity in Greeley, Colorado, are August and September, with an average relative humidity of 44%. On the first day of September in Greeley sunrise is at 6:26 am and sunset at 7:30 pm.
• Longmont - September »
  On the last day of September, in Longmont sunrise is at 6:56 am and sunset at 6:43 pm MDT. In Longmont, Colorado, snow does not fall in June through September.
• Grand Junction - September »
  In Grand Junction, Colorado, during September, the rain falls for 7.3 days and regularly aggregates up to 0.63" (16mm) of precipitation. On the first day of September in Grand Junction, sunrise is at 6:43 am and sunset at 7:44 pm.
• Broomfield - September »
  With the arrival of September, Broomfield notices a mild change in the average high-temperature, sliding from August's warm 84.2°F (29°C) to a still moderately hot 76.6°F (24.8°C). On the first day of September in Broomfield, sunrise is at 6:28 am and sunset at 7:31 pm.
• Castle Rock - September »
  In Castle Rock in September, it is raining for 8.6 days, with typically 0.67" (17mm) of accumulated precipitation. With September's onset, the weather in Castle Rock reveals a slight temperature decrease, transitioning from 82°F (27.8°C) in August to a still moderately hot 75.6°F (24.2°C).
• Commerce City - September »
  In Commerce City during September, the rain falls for 3.3 days and regularly aggregates up to 0.16" (4mm) of precipitation. On the first day of September in Commerce City, sunrise is at 6:28 am and sunset at 7:30 pm.