048
FXUS65 KBOU 190538
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1138 PM MDT Wed Mar 18 2026

.KEY MESSAGES...

- All time March record high temperatures have a high probability
  to be set (80% chance) with upcoming heat through Saturday.
  Daily records almost a certainty.

- Prolonged elevated to critical fire weather conditions due to
  record heat and extremely low humidity levels. Saturday is
  shaping up to be the most critical day as winds increase.

- Brief drop to near normal temperatures Sunday

- Return of unseasonable warmth and potential record heat again
  and more fire weather concerns by Tuesday and Wednesday of next
  week.

&&

.DISCUSSION /Through Wednesday/...
Issued at 1044 PM MDT Wed Mar 18 2026

Not much has changed for the forecast this week as the anomalously
strong upper level ridge continues to dominate our weather pattern
for Colorado through Saturday. Record-breaking heat is still
expected for the next three days, with elevated-to-critical fire
weather conditions (see Fire Weather Discussion below). However,
there is a chance for temperatures to be even warmer than
forecasted, especially Saturday.

700-mb temperatures were around +10 dg C today (Wednesday), which
usually translates to surface temperatures in the mid-to-hihg 70s.
However, with the downsloping winds throughout the day, ACARS
soundings showed steep lapse rates (almost dry adiabatic all the way
up to 500 mb!), allowing warm winds to mix down to the surface. This
resulted in DIA recording a high temperature of 81 dg F.

As the area of High Pressure continues southeast into Mexico, 700-mb
temperatures will increase to +12 dg C on Thursday/Friday and up to
+15 dg C on Saturday. This will support temperatures in the low-to-
mid 80s for the next two days (winds will be weaker as well, so we
are not expecting breezy downsloping winds), and high 80s on
Saturday. However, flat upper level ridging is expected on Saturday
due to a passing shortwave trough north of Colorado. This will
result in gusty downslope winds across the plains. With
compressional heating, it is not out of the question that we could
get up to 89/90 dg F on Saturday. This is further supported by
some of the Canadian and ECMWF ensemble solutions showing max
temperature at DIA of 90 dg F (GEFS/AIGEFS continue to be on the
cooler end of guidance).

All this to say that we will likely beat daily high temperature
records Thursday, Friday, and Saturday for many locations across the
forecast area. And, we will likely beat the all time March high
temperature record on Saturday. Furthermore, with Wednesday`s high
temperature recording of 81 dg F and the expected 80+ dg days
through Saturday, we will have created ANOTHER record for the
longest consecutive 80 dg days in March for the Denver area. The
previous `record` was in 1907, where there were 3 consecutive days
of 80 dg temperatures. Below is an updated max forecast
temperatures from the previous discussion:

Current records and forecast DAILY high temperatures for Denver (DIA):

Thursday, March 19: 81 (1907) / Forecast High: 83
Friday, March 20:   80 (1907) / Forecast High: 84
Saturday, March 21: 78 (1995) / Forecast High: 88

Existing MONTHLY record temperatures for March and max forecasts
through Saturday:

Denver:   83 (1971) / Forecast Max 88
Fort Collins: 81 (2012) / Forecast Max 90
Boulder:   83 (1910) / Forecast Max 87
Greeley:      85 (2010) / Forecast Max 90
Fort Morgan:  85 (2010) / Forecast Max 91
Julesburg:   88 (1967) / Forecast Max 91
Estes Park:   70 (1925) / Forecast Max 76
Dillon:   63 (2012) / Forecast Max 70

As mentioned above, guidance is in good agreement of an upper
level shortwave trough trekking across the northern United states
over the weekend, with an associated cold front (actually more
like a `cool` front) sweeping across the forecast area late
Saturday. Temperatures will moderate to the 60s, which will still
be slightly above normal. Mid-level moisture will be advected into
the region, which could lead to scattered showers Sunday/Monday,
mainly for the mountains. However, any precipitation that does
fall will likely be very light. The 90th percentile of QPF for
ECMWF/ECMWF AIFS/GEFS/AIGEFS showed 0.10"-0.15" of QPF for the
mountains and less than 0.10" of QPF for the plains. Despite the
lack of appreciable precipitation, Sunday will see a brief
reprieve of critical fire weather conditions.

Warm and dry weather returns on Monday and through the middle of the
week, as the upper level ridge begins to restrengthen over the
southwestern United States. Temperatures will likely reach back up
into the 70s and possibly the 80s by Wednesday. In addition,
guidance has indicated a flattening of the ridge, particularly
Tuesday and Wednesday, which would bring gusty westerly winds and
another round of elevated-to-critical fire weather conditions.

&&

.AVIATION /06Z TAFS through 06Z Friday/...
Issued at 1130 PM MDT Wed Mar 18 2026

VFR conditions to remain in place thru the period. WSW winds will
continue thru 08z and then become more SW/SSW at APA and DIA. BJC
will stay mainly west.  On Thu, winds will become WSW/W at all
three sites by 17z. In the aftn there is some disagreement on
wind speeds and directions. Some data suggest, there will be a
weak Longmont Anti Cyclone which may keep directions light N/NNE
at APA and DIA thru much of the aftn until 22z or 23z when winds
go more NW with a few brief gusts up to 25 mph until 01z.
Confidence in this scenario is low at this time so will keep winds
more WNW/NW with some gusts to 25 mph thru 01z.


&&

.FIRE WEATHER...
Issued at 1044 PM MDT Wed Mar 18 2026

For Thursday, critical fire weather conditions are expected for
areas near the Cheyenne Ridge, where a current Red Flag Warning is
in effect from 11 AM - 7 PM. Near-critical fire weather conditions
are possible in the valleys of North Park, as relative humidities
are expected to dip down to around 15% and fuels have just been
deemed critical. However, winds will be relatively marginal, with
gusts up to 20 mph are expected, with brief gusts of 30 mph. Have
opted out of including North Park in a RFW for now. However, if
new guidance shows stronger winds, will need to include that area
for tomorrow. For the rest of the region, widespread elevated fire
weather conditions are expected throughout the day. However, winds
will be weaker on Thursday than they have been for the past two
days. West/northwest wind gusts will generally stay below 25 mph,
with only the Urban Corridor occasionally seeing gusts up to 30
mph at times in the afternoon.

Elevated fire weather conditions are expected across the forecast
area on Friday with the continued warm and dry conditions.
However, winds will be the limiting factor for any critical fire
weather conditions, as west/northwest wind gusts should generally
remain under 25 mph. The only exception would be the northern
plains near the Cheyenne Ridge. Due to low confidence of stronger
winds in that area, have opted out of a Fire Weather Watch and
will let the next forecaster re-evaluate.

Saturday remains to be the highest concern for widespread near-
critical to critical fire weather conditions, as that will be the
warmest and `driest` day. Fuels will continue to be critical
across the plains, and fuels have just recently been deemed
critical in areas along the high terrain. Minimum relative
humidity values will range between single digits in the plains,
and teens-to-low-20s across mountains and valleys. In addition,
with the upper level ridge flattening due to a passing shortwave,
widespread gusty westerly winds are expected.

There will be a brief reprieve of fire danger on Sunday, as a cold
front will bring in a slightly cooler air mass and some 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 Wednesday.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 7 PM MDT Thursday for COZ238-242.

&&

$$

DISCUSSION...MAI
AVIATION...RPK
FIRE WEATHER...MAI

NWS BOU Office Area Forecast Discussion