September 2026 will be remembered as the month that put an exclamation point on an extraordinary water year of heat and dryness in Boulder, with less than 20% of normal precipitation falling during the month and temperatures more than five degrees above average. Despite a strong late-season monsoon, moisture largely avoided the Front Range, and especially Boulder County, culminating with a great modeling collapse of a significant rain event in the final days of the month tied to the remnants of Hurricane Polo.
Here’s a graphical look at how September 2026 unfolded across Boulder, Denver, and the Front Range — and how it compared to climatology.
