September weather forecast
Wyoming, USA

September marks the onset of autumn in Wyoming, bringing with it a notable shift in climate and scenery. Average low temperatures begin to drop, generally ranging from 40°F (4.4°C) to 50°F (10°C), while average high temperatures in the plains may reach up to 75°F (23.9°C). In the highlands, expect temperatures to peak between 60°F (15.6°C) and 70°F (21.1°C). The month also sees a reduction in precipitation, although the range varies from 8" (203mm) in the lowlands to 15" (381mm) in the higher elevations.

Relative to August, September experiences shorter days and cooler temperatures, signaling the transition into fall. Winds maintain their presence but are generally not as intense as in the summer months. Thunderstorm activity decreases considerably, making room for more stable weather patterns. September is especially popular for its scenic appeal, as foliage in the high country starts to change color, offering a vibrant landscape. The tourist season continues but at a slower pace, making it an excellent time for visitors who prefer fewer crowds while still enjoying good weather and outdoor activities.

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• Cheyenne - September »
  As August transitions into September, Cheyenne sees a gentle drop in the average high-temperature, transitioning from 81.1°F (27.3°C) to a still warm 73.8°F (23.2°C). In Cheyenne, in September, it is raining for 8.4 days, with typically 0.87" (22mm) of accumulated precipitation.
• Casper - September »
  The months with the least rainfall in Casper are January, August and September Rain falls for 7.6 days and accumulates 0.43" (11mm) of rain. The months with the least rainfall in Casper are January, August and September Rain falls for 7.6 days and accumulates 0.43" (11mm) of rain.
• Laramie - September »
  In Laramie during September, the rain falls for 9.9 days and regularly aggregates up to 0.98" (25mm) of precipitation. On the first day of September in Laramie sunrise is at 6:28 am and sunset at 7:35 pm.
• Gillette - September »
  In Gillette, during September, the rain falls for 10.2 days and regularly aggregates up to 1.02" (26mm) of precipitation. In September, in Gillette the rain falls for 10.2 days.
• Rock Springs - September »
  In Rock Springs, during September, the rain falls for 7.2 days and regularly aggregates up to 0.63" (16mm) of precipitation. In Rock Springs, during September, the rain falls for 7.2 days and regularly aggregates up to 0.63" (16mm) of precipitation.
• Sheridan - September »
  In Sheridan, in September, during 12.5 rainfall days, 1.42" (36mm) of precipitation is typically accumulated. On the first day of September in Sheridan, sunrise is at 6:30 am and sunset at 7:45 pm.
• Green River - September »
  In Green River, Wyoming, during September, the rain falls for 7.2 days and regularly aggregates up to 0.63" (16mm) of precipitation. In Green River in September, during 7.2 rainfall days, 0.63" (16mm) of precipitation is typically accumulated.
• Evanston - September »
  In Evanston in September, during 8 rainfall days, 0.71" (18mm) of precipitation is typically accumulated. In Evanston, in September, during 8 rainfall days, 0.71" (18mm) of precipitation is typically accumulated.
• Riverton - September »
  On the first day of September in Riverton sunrise is at 6:38 am and sunset at 7:48 pm. On the last day of September, in Riverton, Wyoming, sunrise is at 7:09 am and sunset at 6:57 pm MDT.
• Jackson - September »
  In Jackson, Wyoming, in September, during 10.8 rainfall days, 1.77" (45mm) of precipitation is typically accumulated. In Jackson, in September, snow falls for 3.3 days, with typically accumulated 5.12" (130mm) of snow.
• Cody - September »
  In Cody during September, the rain falls for 6.5 days and regularly aggregates up to 0.59" (15mm) of precipitation. On the first day of September in Cody, sunrise is at 6:38 am and sunset at 7:53 pm.
• Rawlins - September »
  In Rawlins snow does not fall in June through September. Fall claims Rawlins in September, leading to comfortably warm days and cool, breezy evenings.