A giant ridge—basically, a large area of high atmospheric pressure—is setting up over the Four Corners region this week, and it’s bringing with it clear skies and rapidly rising temperatures.

In fact, temperatures are supposed to spike so much that the National Weather Service issued the first-ever excessive heat warnings in Colorado history on Monday for parts of the Western Slope, including the Grand Valley, which will remain in effect until Friday. Temperatures in that region are supposed to reach 105 to 110 degrees throughout the rest of the week, possibly breaking monthly and all-time highs.

Denver won’t be spared from that heat wave, either: Temperatures could hit 100 degrees several times this week, including on Tuesday, Wednesday, and Thursday, before a cold front moves in on Thursday afternoon and gives us a break from the scorching June sun. Temperatures in the high country will also run 10 to 20 degrees hotter than normal because of the warmth created by the ridge. It’s even possible that record highs could be set in some of the higher elevations.

The reason this ridge promises to bring such intense heat is due, in part, to the fact that the Western Slope is already facing extreme drought conditions. The air has limited moisture, which typically takes up some of the sun’s energy during the evaporation process. That means temperatures will soar higher than they would if there were adequate water around.

Unfortunately, the tiny amount of moisture that the brush and trees hold will also evaporate and dry out quickly, if it hasn’t already, making the vegetation better fuel for any potential wildfires. Fire danger, as you can imagine, will be very high this week.

There is a chance some subtropical moisture could wedge itself underneath the ridge by midweek, allowing for limited rain storms (most likely for the mountains). But due to the intensity of the heat, rain could also have a hard time making it to the ground. That means dry thunderstorms, and the chance of lightning igniting new fires, are a high possibility.

If you do plan to be outside in the next few days, drink plenty of water and take breaks in the shade. And don’t leave any pets, children, or elderly persons in vehicles—where temperatures could soar well above 120 degrees—for any reason.

We should get back to more normal weather patterns by the end of the week, with the chance of afternoon thunderstorms back in the forecast.

Andy Stein
Andy Stein
Andy Stein is a freelance meteorologist with experience working on both local and national television.