National Weather Service Boulder has issued a flood watch for several counties, including Pitkin, Eagle and surrounding areas.
The watch is in effect until midnight Tuesday.
Residents can expect excessive runoff due to flooding rivers, creeks, streams and other low-lying and flood-prone locations. Creeks and streams may rise out of their banks, and low-water crossings may be flooded.
Flash flooding and debris flows caused by excessive rainfall are possible over the Grizzly Creek Fire Burn Area.
East of the Denver and Pueblo metro areas, strong, slow-moving thunderstorms will develop later this evening.
The storms are also predicted to move into the Front Range with a potential for locally heavy rainfall.
Storms near Denver have already produced flash flooding with 1 to 3 inches of rain in a very short time.
Weld, Larimer and Boulder county are under a hazardous weather outlook.