Jamestown, North Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

076
FXUS63 KBIS 252330
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
630 PM CDT Sat Jul 25 2026

.KEY MESSAGES...

- Very hot conditions through the weekend, with dangerously high
  temperatures and heat index values around 100 to 105 degrees.

- The combination of hot, dry, and breezy conditions on Sunday
  may cause near-critical fire weather conditions in parts of
  western and central North Dakota.

- The very hot temperatures may continue into Monday southwest,
  with a slight drop in temperatures elsewhere. The rest of the
  week remains hot with highs mostly in the 90s, but with some
  reading above 100 degrees possible in southwest North Dakota.

- Daily low to medium (20-40%) chances for thunderstorms remain
  in the forecast through the work week.

&&

.UPDATE...
Issued at 630 PM CDT Sat Jul 25 2026

Isolated weak radar returns linger over portions of the far
southwest at the time of this early evening update. Later this
evening into early tonight, showers and storms currently
developing upstream in central Montana are expected to begin
moving toward the ND/MT border. Short term CAMs continue to have
difficulty resolving the longevity of these storms due to the
fairly robust capping expected to be in place over western North
Dakota by this time, though one or two models continue to
propagate at least some showers and storms across western North
Dakota into central North Dakota overnight. Considering this,
have opted to spread low PoPs (less than 20 percent) overnight
through early Sunday morning. In the scenario where storms do
end up diminishing rapidly as they cross over the ND/MT border,
there is some potential for isolated strong winds as the very
hot and dry vertical column across western North Dakota would be
supportive of heat bursts. All of that is to say, we will need
to monitor conditions as we head into the evening.

&&

.DISCUSSION...
Issued at 250 PM CDT Sat Jul 25 2026

Very hot temperatures continue across much of western and
central North Dakota this Saturday afternoon. Hettinger had
already reached 104 degrees as of noon MDT. Many other locations
south and west of the Missouri River are also around the 100
degree mark early this afternoon. In Bismarck, our morning fog
held temperatures down a bit through mid morning, but we are
catching up quick with an early afternoon reading in the mid
90s. The Heat Advisory started at 1 PM CDT and no changes here
with temperatures and/or heat indices in the 100-105 range for
the Advisory area.

The risk for thunderstorms remains low tonight, especially over
northern and eastern portions of the forecast area. The better
forcing for ascent will remain over southeast Montana into
northwest South Dakota, yet a stronger storm or two can not be
ruled out in the far southwest, producing a marginally severe
wind gust.

Sunday will be a repeat of today temperatures wise, with
forecast highs once again expected to be over 100 degrees over
much of the southwest and south central. Only slightly cooler
temperatures in the 90s are anticipated along the International
Border. The very hot temperatures should keep thunderstorm
chances to a minimum. If anything, perhaps an isolated
shower/storm brushing the International Border Sunday morning,
and possibly some dissipating convection moving into the west
later Sunday night. Most of the day will be sunny and hot. The
threat for severe storms Sunday is minimal.

The very hot and dry conditions Sunday, combined with a dry cold
front passage, may create near critical fire weather concerns
Sunday afternoon and early evening. Afternoon relative
humidities will drop to 12 to 18 percent across much of western
North Dakota. Northwest winds will increase behind the dry cold
front to 15 to 20 mph with gust to 30 mph. Due to the recent dry
conditions, grasses have begun to cure and near critical fire
weather conditions may be reached.

On Monday, the upper level ridge over the Northern Plains
flattens a little bringing cooler temperatures northeast, but
with very hot temperatures still possible in the southwest and
far south central. Will hold off on any extensions of the Heat
Advisory, but this is something that may be needed as we get
closer to Monday. As was mentioned above, daytime thunderstorm
activity will be suppressed due to the hot temperatures. A
morning or overnight isolated thunderstorm can not be ruled out
though.

The remainder of the work week will continue to bring hot
temperatures, mainly in the 90s, but with some 100 degree
readings still possible in the southwest. Overall though, not
quite as hot as this weekend. Daily low chances (20-30%)
thunderstorm chances will remain through the week but with a low
predictability in when and where they may occur. There does
look to be a little better chance of precipitation in the
Wednesday/Thursday timeframe with another impulse that briefly
flattens the mean upper level ridge.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 630 PM CDT Sat Jul 25 2026

VFR ceilings and visibility are generally expected at all
terminals throughout the 00Z TAF period. Late this evening and
tonight, scattered showers and a few thunderstorms may cross
into western North Dakota and move into south central North
Dakota through tomorrow morning. Confidence on coverage and
location is very low, and thus no mentions have been included at
any give TAF site. Otherwise, patchy fog is possible over
portions of the James River Valley overnight, though confidence
in visibility impacts at KJMS are also very low at this time.
Light and variable winds are generally expected this evening
tonight, before strengthening and turning cyclonically around a
low pressure system passing to the north of the forecast area
Sunday morning and afternoon. Wind speeds up to around 15 knots
and gusts up to 25 knots are expected Sunday afternoon, mainly
west.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 9 PM CDT /8 PM MDT/ Sunday for NDZ017>020-
022-023-025-031>033-035>037-040>044-046>048-050-051-057>062.

&&

$$

UPDATE...Adam
DISCUSSION...TWH
AVIATION...Adam