Denver

Denver to Face Sweltering Heat, Isolated Storms, and Ozone Alert This Week

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Published on August 20, 2025
Denver to Face Sweltering Heat, Isolated Storms, and Ozone Alert This WeekSource: Flickr, CC BY 2.0, via Wikimedia Commons

Denver residents are bracing for a mix of weather conditions over the next few days, with sunny skies giving way to showers and thunderstorms. According to the National Weather Service, today will be sunny with a high near 95 degrees, followed by a mostly clear night with a low around 65 degrees. Winds could gust as high as 15 mph.

The calm weather will not last long as Thursday is expected to be hotter with temperatures nearing 99 degrees and the possibility of isolated showers and storms in the afternoon, particularly for the Palmer Divide and the mountains. The hazardous weather outlook has pointed out that these storms could produce gusty outflows between 35-45 mph. A marked change is anticipated Friday onwards, with a cold front bringing in a 60% chance of showers and thunderstorms throughout the weekend.

In tandem with the weather, an Ozone Action Day Alert has been declared by the Colorado Department of Public Health and Environment for the Front Range Urban Corridor. This includes Douglas, Jefferson, Denver, western Arapahoe, western Adams, Broomfield, Boulder, Larimer, and Weld Counties. The Department remarked, on Wednesday, hot and stagnant conditions will allow ozone to reach the Unhealthy for Sensitive Groups category. This heightened level of ozone pollution underscores the importance not just of policy action but also of individual choices, as residents are encouraged to limit their use of gas and diesel-powered vehicles at least until 4 p.m. on Wednesday, August 20.

The impact of increased ozone levels is not to be underestimated, as it brings an increasing likelihood of respiratory symptoms and breathing discomfort in active children and adults and people with lung disease, such as asthma, according to health information provided by the department. Those at risk are advised to reduce prolonged or heavy outdoor exertion. With the weekend promising scattered to numerous showers and storms due to a northwesterly flow aloft, it appears that the state's weather and environmental concerns will be closely intertwined.

Denver-Weather & Environment