textproduct: Sioux Falls

KEY MESSAGES

- Near record to record temperatures expected to continue through Saturday.

- Fire danger will become elevated to critical in a brief window Saturday afternoon along the Missouri River valley. Any burning activities should be postponed.

- The passage of a front Saturday night will bring cooler temperatures into next week, with a very low risk of sprinkles to light rain. Gusts may reach 40+ mph briefly Saturday night.

- A roller coaster ride of temperatures and wind can be expected next week, increasing fire danger, but with little to no rain anticipated.

DISCUSSION

Issued at 1214 PM CDT Fri Mar 20 2026

THIS Afternoon: Yet another spectacular mid-March afternoon across the Tri-State area as temperatures continue to rise through the 60s and into the 70s. A few 80s will also be possible along the MO River valley. While RH values are falling into to 20% range south of I-90 this afternoon, winds remain below RFW criteria.

TONIGHT: The passages of mid-lvl vorticity will clear out cirrus overnight tonight, with light and variable winds developing through the evening. These winds will become more southerly or southwesterly through the night, allowing the diurnal temperatures fall to stability or even rise into daybreak Saturday.

SATURDAY: A near record to record day is expected through the region on Saturday as temperatures are expected to soar into the upper 70s and 80s in the afternoon. A few locations along the Missouri River valley may reach the 90 degree mark. A very dry day is expected Saturday, increasing fire weather concerns in the afternoon. The greatest risks are likely found along or mostly south of the Missouri river valley and Highway 20. Please see separate fire weather discussion for more details.

SATURDAY NIGHT: Guidance remains consistent bringing a strong cold front southward Saturday evening and tracking south through the night. This front enters the Highway 14 corridor around 00Z, enters areas south of I-90 by 10pm, and clears the CWA by 1am. Latest guidance continues to show a tight SPG developing behind the front, suggesting sustained winds of 20+ mph are possible. The strong cold advection behind the boundary will create a steep low-lvl lapse rate into Sunday morning, suggesting an increased possibility for 35 to 45 mph gusts into daybreak. Given the NBM low bias in these setups, have blended in more 90th percentile and high resolution CAM winds.

SUNDAY: Cold advection persists through Sunday, with with a rather breezy sustained wind through the day. After reaching the 80s Saturday afternoon, daybreak wind chills in portions of the CWA will be nearly 60 degrees colder. Temperatures in the afternoon will rebound back to the upper 40s to lower 50s in most locations. Latest ensemble guidance continues to back off on the potential for measurable rainfall Sunday morning, though the presence of lower stratus could still result in sprinkles north of I-90.

MONDAY-WEDNESDAY: The forecast remains on track for the first half of next week as quasi-zonal flow to an amplified ridge pattern develops. Initial cold air mass that advects southward Sunday will quickly become shunted eastward as lee-side troughing redevelops over the Western Plains. Low-lvl thermal advection will increase first over central South Dakota, aligned with an increased SPG. There remain some hints at low-lvl moisture transport into the Dakotas early Monday which could result in isolated to scattered showers. Further east, increasing surface winds will begin to heighten fire danger risks by mid-late afternoon.

Temperatures warm further Tuesday and Wednesday as the orientation of low-lvl warm advection spread eastward and over the Tri-State area. We'll again see temperatures climb into to 60s and then 70s by Wednesday. One thing that we'll need to keep a close eye on is the mixdown of dry air each afternoon. Given the persistent southerly to southwesterly surface flow off the drier Central Plains, we could see significantly lower dewpoints develop than what the deterministic NBM suggests. The full range of NBM guidance would suggest a nearly 10-15 degree spread in the 25/75th percentile dew point values each afternoon. This difference represents the potential for 20-25% RH vs the currently forecast 35% RH values and when combined with afternoon gusts approaching 25+ mph could result in higher fire weather concerns both days.

THURSDAY-FRIDAY: We'll finish the work week with another strong cold front plunging southward by Thursday. Behind this front, another round of gusty northwest winds are likely, with highs falling back to the 40s by Friday. The expectation given agreement in ensemble data is that little to no impactful precipitation is expected through next week. Long range LREF guidance through next Saturday only suggests a 10-20% probability for more than 0.10" of QPF over the 7 day forecast, with a 0-5% probability of more than 0.25" at any one point.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1201 PM CDT Fri Mar 20 2026

VFR conditions are expected into Saturday. Winds remain light this afternoon and turn variable in direction after sunset. Cirrus will continue at times into Saturday.

FIRE WEATHER

Issued at 1214 PM CDT Fri Mar 20 2026

Temperatures will continue to rise near record values through Saturday afternoon. With very dry soils we're also expecting to see relative humidity values fall as low as 10 to 20% in areas along and south of I-90, with the lowest conditions near the Missouri River and Highway 20. The biggest variable of the fire weather forecast remains winds on Saturday. Latest guidance shows a narrow window after 1-2pm where a brief bout of 20-28 mph gusts may develop from south central SD eastward along the river for a few hours before subsiding early in the evening as a front moves closer.

Feel given the degree of heating and potential mixing, will hedge closer to the 75/90th percentile of HREF wind guidance. The resultant GFDI values push the high to very high levels in areas south of I-90, but the extremely low RH may compensate for lower winds to still allow explosive fire growth to occur in fine fuels along the MO River. As a result, will issue a confined RFW for areas along the river. Future forecasts may make adjustments to areas of NW Iowa, where confidence on duration of highest potential is much lower than further west.

CLIMATE

Issued at 1253 PM CDT Thu Mar 19 2026

Extremely warm air will try to move eastward late this week into this weekend. These temperatures may result in the top 10 earliest 75 and 80 degree highs at long term climate locations. Here is a look at records for Friday and Saturday

Record High Temperatures:

March 20: KFSD: 73/2022, KSUX: 79/2015, KHON: 75/1911, KMHE: 77/1994

March 21: KFSD: 83/1910, KSUX: 85/1910, KHON: 84/1907, KMHE: 88/1907

Record High Minimum Temperatures:

March 21: KFSD: 49/1938, KSUX: 48/2012, KHON: 45/1938

FSD WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning from 1 PM to 10 PM CDT Saturday for SDZ050- 063-068>071. MN...None. IA...None. NE...Red Flag Warning from 1 PM to 10 PM CDT Saturday for NEZ013- 014.