textproduct: Bismarck

KEY MESSAGES

- Cooler today with a few showers in the southwest.

- Warming temperatures and mainly dry conditions expected through Thursday.

- Very hot conditions expected to return Friday through the weekend, with high temperatures and heat index values potentially above 100 degrees.

UPDATE

Issued at 833 AM CDT Tue Jul 21 2026

The forecast remains on track.

UPDATE Issued at 630 AM CDT Tue Jul 21 2026

Limited updates needed this morning. Some northern sites are reporting reduced visibility in haze and mist. This could be patchy fog trying to form, with high clouds limiting it, some patchy smoke moving in, or a combination of both. Have kept patchy fog through the mid morning to account for the patchy fog potential. Otherwise the forecast overall remains on track.

DISCUSSION

Issued at 335 AM CDT Tue Jul 21 2026

Light winds and high RH values could bring some patchy fog this morning, although mid to high level clouds look to limit this threat. Some lower clouds may also be found in the southeast this morning. Stalled surface front with northwest flow aloft will bring a brief cool down today. High temperatures will generally be in the mid 70s to lower 80s, which will be slightly below normal for most locations. Wind will be less windy today with a surface high to our north. The stalled front could bring a few high based showers to the southwest today, with a low threat for thunderstorms. Some haze or patchy wildfire smoke is also possible today given the northwest flow aloft. Surface high moves across the region tonight bringing mainly clear skies and cooler lows in the 50s. Light winds combined with clear skies and cooler temperatures could bring some patchy fog, although confidence was not high enough to include at this time. Wednesday through Thursday, surface high moves eastward while an upper level ridge begins to build back into the area. Southerly flow at the surface will begin to warm temperatures back to normal to perhaps slightly above normal readings. Dewpoints should remain low, limiting the heat risk. Depending on placement of the upper level ridge, northwest flow aloft could bring some weak waves in the flow and perhaps some low precipitation chances. Instability looks limited on Wednesday, although becomes slightly more increased on Thursday, with perhaps and isolated thunderstorm possible. Right now the NBM has a mainly dry forecast, with better chances for precipitation in South Dakota.

Friday through the weekend, large upper level ridge looks to shift just enough to the east to return very hot temperatures and perhaps some dangerous heat risk. Forecast highs in the 90s to low 100s, and low temperatures in the 60s remain in the forecast. There could still remain some heating bias from the last warming trend in the NBM, although the NBM spreads at least indicate another strong warming trend coming this weekend. Much lower dewpoints will be found for this upcoming weekend's heat. Even so Heat Risk and Wet Bulb Global Temperature values are showing high to extreme heat risk. Heat Index Values may also be near to above 100 degrees especially on Saturday. Will continue to monitor for potential heat products. Depending how strong the ridge builds there could be near daily chances for showers and thunderstorms Friday through the weekend with any ridge rider type waves. These same disturbances could bring some increased winds at times this weekend. This combined with low afternoon humidity values in the teens and 20s may also bring an increased fire weather threat this weekend. Overall those with outdoor plans will want to start planning for a hot weekend with some slight shower and thunderstorm chances.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 630 AM CDT Tue Jul 21 2026

Some low clouds and patchy fog could bring MVFR to brief IFR conditions this morning, mainly in the west and north. Confidence was only high enough to include a TEMPO group for MVFR ceilings at KDIK this morning. Confidence was too low to include fog mention at this time. Look for VFR conditions for the remainder of today through tonight. Northerly winds will linger for today becoming east northeast this evening, then light and variable for most sites. A few light rain showers are possible in the southwest today. Some wildfire smoke may also return to the region today, although confidence in any visibility or ceiling impacts is low.

BIS WATCHES/WARNINGS/ADVISORIES

None.