textproduct: Denver/Boulder

KEY MESSAGES

- Heat peaks on Saturday with all time March records being broken by several degrees! A few locations may see 90F Saturday afternoon.

- Widespread critical fire weather conditions expected on Saturday due to record heat, breezy winds, and extremely low humidity levels. - Brief drop to near normal temperatures Sunday.

- Return of unseasonable warmth, potential record heat (>70% chance), and more fire weather concerns again by Tuesday and Wednesday.

DISCUSSION /Through Friday/

Issued at 1038 PM MDT Fri Mar 20 2026

Another day, another daily max temperature record broken. DIA recorded a high temperature of 85 F, which not only breaks the daily record set in 1907, but also ties the monthly high temperature record that was just broken yesterday. With this heatwave peaking tomorrow as the well-advertized upper level ridge treks southeast, we will very likely (>90% chance) break daily and monthly records yet again.

Guidance continues to be in good agreement of 700-mb temperatures reaching up to +15 C across the plains, which would roughly translate to high 80s F at the surface for the plains. However, with a passing shortwave over northern U.S., the ridge will begin to flatten, leading to widespread breezy downslope winds by late morning/early afternoon. Despite recent hi-res models slightly delaying the onset timing of downslope winds onto the plains, there should be enough in the afternoon to allow compressional heating to bump temperatures to 89/90 F and create widespread critical fire weather conditions (see Fire Weather Discussion below). If DIA reaches 90 F tomorrow, it will be the first 90 dg day recorded in the month of March for DIA. The only caveat that would keep us from reaching the forecasted high would be the incoming cloud cover from the associated shortwave. Relative humidity cross-sections do indicate high cirrus clouds by late afternoon/early evening.

Sunday will see a brief reprieve of record-breaking temperatures, as the shortwave to our north pushes a "cool" front across the region Saturday night. Mid-level moisture will be advected into the region on Sunday, allowing surface relative humidities get above 20%. However, little, if any, precipitation is expected with this system, as global ensembles show less than 0.10" of QPF along the high terrain, and T for the plains. Temperatures should moderate to the mid 60s, however that still puts us ~10 degrees above normal!

Warm and dry weather returns early next week as the upper level ridge begins to restrengthen over the southwestern United States. The ridge will be slightly more elongated over the region, which will likely result in another round of westerly downslope winds and compressional heating. Record-breaking temperatures are possible once again, with ensemble guidance indicating temperatures in the 80s by Wednesday. Elevated-to-critical fire weather conditions are also possible.

A little uncertainty in the forecast past Wednesday, as a shortwave trough with an associated cold front will pass sometime Thursday or Friday. With the most recent run of the NBM trending warmer for max temperatures on Thursday, cold front may arrive closer to Friday. Ensemble guidance continues to indicate light, if any, precipitation for the mountains with this system as well.

AVIATION /18Z TAFS through 18Z Sunday/

Issued at 1146 AM MDT Sat Mar 21 2026

The west-northwesterly winds aloft will eventually get down to the surface later this afternoon with the strong heating. Will go with gusts up to around 25 knots. Will go with lighter west winds by mid evening until the cold front moves in after midnight. Left the 09Z timing of that feature in the TAF. Gusts may reach 20 knots behind the FROPA. Cross section on some of the models still hint at a deck of Stratus after the front goes through. Will leave that going in the TAF for now but I am somewhat skeptical.

BOU WATCHES/WARNINGS/ADVISORIES

Red Flag Warning from 11 AM to 10 PM MDT Saturday for COZ211- 213>216.

Red Flag Warning from 2 PM to 10 PM MDT Saturday for COZ238>245- 248-250.

BOU WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 10 PM MDT this evening for COZ211-213>216.

Red Flag Warning until 10 PM MDT this evening for COZ238>245-248- 250.