Average September Weather:

Greeley averages: high 83; low 48, with 3 days of rain. Average snowfall 1 inch. 


Daily high temperatures rarely fall below 58°F or exceed 92°F.

Daily low temperatures 41°F, rarely fall below 33°F or exceed 59°F.


The Old Farmers Almanac projects a long range forecast that September and October 2020 will have above-normal temperatures and below-normal precipitation. We’ll see what they say about September 2021 when the time comes.

"Climate is what you expect; weather is what you get." Robert A. Heinlein

Colorado’s weather is notoriously variable. The state receives over 300 days of sunshine a year. Our diverse terrain, altitude, dry air and micro-climates mean that it could be snowing in the mountains while it is a scorching hot day on the plains.


In addition, our day and night temperature variations feature a much greater swing than most other locations in the US. Particularly in the Spring and Fall, it’s not unusual to have a 40-degree difference between the high and low temperatures for the day. Once the sun goes down, the temperature quickly sinks, usually working its way to the daily low around 5:00 am.


What This Means for You:

You’ll need to pack creatively, utilizing a layering method.  Bring clothes that can be easily added to a base layer if the morning is chilly, and then shed later in the day as the sun rises higher in the sky. You’ll likely be wanting to add 1-2 layers back by sunset. Just in case Greeley gets a dusting of snow while you're here, you may want to pack a medium weight jacket--or buy one from the 2021 Specialty store while you're here!


Greeley is at 4,675 feet in altitude. Combined with our intense sunshine, you’ll be needing sunscreen several times each day, and maybe a hat and sunglasses.

For tips on adjusting to the altitude, see Altitude Tips page.

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Puppy and Colorado Mountains
Hiking in CO
Little Girl and Her Dog
Changing Leaves