4:50 PM MDT, Sunday, September 29, 2019
A cold front late Monday will bring the coolest weather so far this season Monday night through Wednesday morning. We are not expecting any early-season snow in the urban corridor, but it might get a bit damp by Tuesday morning.
Most of the daytime hours on Monday will be ahead of the front, so another warm day is likely. It may start to cool by late in the day, especially in southeastern Wyoming. Cool upslope (northeasterly) flow Monday night will bring in the cooler air. For the lower foothills and plains (including the urban corridor) there is a good chance for a period of low clouds and areas of fog and drizzle late Monday night into Tuesday. Depending on how quickly those clouds thin out, Tuesday could have a high in the 50s for Denver, Boulder, and Fort Collins.
With clearing skies likely Tuesday night we are likely to see some local frosts in the normally colder spots such as the river valleys in northeastern Colorado. Milder weather is likely to make a comeback Wednesday afternoon.