785
FXUS65 KBOU 211120
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
520 AM MDT Sat Mar 21 2026

.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 /12Z TAFS through 12Z Sunday/...
Issued at 515 AM MDT Sat Mar 21 2026

VFR conditions are favored to prevail for the terminals through
the TAF period (and certainly through at least 10Z Sun).

Current drainage flow has weakened slightly with some minor
oscillations between SW and SE flow at times for KDEN/KAPA. Expect
continued light drainage with some variability in direction to
continue through the morning, with westerly flow prevailing for
KBJC.

West winds are eventually expected to mix down, starting near 21Z
for KBJC and closer to 22-23Z farther east. A few gusts 20-25 kts
will be possible for a 2-4 hr window, diminishing after ~02Z this
evening. Favoring continued W flow late evening until a cold front
arrives near 07-08Z Sun, shifting winds out of the north. Short
window of gusts near 20 kts will be possible with the front,
weakening thereafter with northeast flow prevailing into Sunday
morning.

FEW-SCT low clouds with bases 020-030 look possible mainly after
13Z Sun, with best chances for KDEN, though confidence is low.
Chance of CIGS is ~20%.

&&

.FIRE WEATHER...
Issued at 1038 PM MDT Fri Mar 20 2026

Widespread critical fire weather conditions expected on Saturday.
Record warmth and minimum relative humidity values below 15% across
the mountains, and below 10% for mountain valleys, foothills, and
plains by the afternoon. With westerly flow aloft, winds will
begin mixing down to the surface in the morning for mountains &
foothills, and mixing down into the plains by the early afternoon.
Strongest winds will likely remain west of the far eastern
plains. A Red Flag Warning is in effect from 11 AM (high
terrain/foothills) / 2 PM (plains) to 10 PM.

There will be a brief reprieve of fire danger on Sunday, as a cold
front will bring in a slightly cooler air mass and moisture.
However, that will be short-lived as warm and dry conditions will
return with the upper level ridge rebuilding. Elevated to critical
fire weather conditions are possible Tuesday and peaking Wednesday
as winds strengthen.&&

.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 from 11 AM this morning to 10 PM MDT this
evening for COZ211-213>216.

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

&&

$$

DISCUSSION...MAI
AVIATION...BRQ
FIRE WEATHER...MAI

NWS BOU Office Area Forecast Discussion