textproduct: Sioux Falls

KEY MESSAGES

- Frost is expected early this morning. A Frost Advisory is in effect until 9 am.

- Today, Tuesday and Thursday will see elevated to near critical fire weather concerns. Tuesday and Thursday appear to carry the highest risks with very strong winds with a dry air mass.

- Warmer conditions are expected this week with highs 10 to 20 degrees above normal. Thursday and Friday should see highs in the mid 80s to lower 90s.

- Dry weather remains for most of the week. Starting to see increased chances for showers and thunderstorms late week into the weekend.

UPDATE

Issued at 308 AM CDT Mon May 11 2026

High pressure at the surface drifts east and allows southerly flow to develop today. Wind gusts of 25 to 35 mph are likely, especially near and west of I-29. With the relative humidity falling to 20 to 30 percent, elevated fire danger is expected.

Low pressure tracks by to the northeast of the area, swinging a front through tonight into Tuesday morning. This will bring stronger northwest flow and continued dry air, leading to elevated to near critical fire weather conditions. Fire weather headlines will likely be needed with relative humidity once again averaging 20 to 30 percent in the afternoon and wind gusts climbing to 30 to 40 mph.

After a pleasant Wednesday, Thursday will see very strong southerly flow develop. This is another day when fire weather headlines will likely be needed. Afternoon relative humidity will once again averaging 20 to 30 percent with wind gusts 35 to 45 mph.

DISCUSSION

Issued at 153 PM CDT Sun May 10 2026

Partly clear skies persist this afternoon, allowing high temperatures to warm to the 60s and 70s. Low humidity and marginally breezy winds will keep elevated fire danger conditions going through the rest of the afternoon hours. Temperatures tonight remain on track to be on the cold side once again, falling to the low to mid 30s to low 40s. Thus, have issued another Frost Advisory for locations along and northeast of a Huron, South Dakota to Sioux Falls, South Dakota, to Orange City, Iowa line. The Frost Advisory is in effect from 3 am to 9 am Monday.

An upper level trough will begin to push into the Northern Plains from Canada on Monday. Warm air advection (WAA) will strengthen ahead of this wave throughout the day. The WAA will push high temperatures above average across the area with highs into the 70s and 80s expected. Dew points will remain low though, resulting in humidity values down to near critical to critical levels. The low humidity along with breezy southerly winds with gusts up to 20-35 mph, strongest along and west of I-29, will result in another day of elevated fire danger across the area. While conditions will be near critical to critical, greening fuels continue to lessen the overall fire danger. A cold front tied to this upper wave will push through the area during the overnight hours. The low level jet (LLJ) will strengthen ahead of the front, keeping breezy winds going through the night. A few showers to perhaps a thunderstorm or two could develop along the front as well. Severe weather is not expected as instability will be quite weak, but perhaps some gusty winds could be possible. Low temperatures will be much warmer, only falling to the 50s overnight.

Tuesday and Wednesday look to remain warm across the area as upper level ridging builds over the central CONUS. Tuesday will be the cooler of the two days with high temperatures warming to the 70s. However, winds will be quite breezy out of the northwest within the post frontal cold advective airmass with gusts up to 30-40 mph. Humidity values will be low across the vast majority of the area and will hit critical thresholds. Despite recent greening of fuels, Tuesday continues to have the highest fire danger potential with a high GFDI. Wednesday will be a little bit warmer with highs in the 70s to low 80s. The low humidity will persist but winds will be much lighter, keeping fire danger at bay.

There remains uncertainty regarding how the upper level pattern will evolve for the rest of the work week and weekend. Medium range guidance, including the machine learning guidance, continue to vary on how the shortwave trough over the west coast progresses. The main two camps that the models are split over is whether the upper low slows down and potentially cuts off over the west coast or continues eastwards as a more progressive shortwave. If the wave stays progressive, then rain chances could increase beyond what they currently are (20-30%). If the waves cuts off, then chances for rain could diminish. Tough to say which solution is most likely at this time but something that will be monitored over the coming days. Aside from rain chances, Thursday and Friday continue to look very warm with high temperatures warming into the 80s across the area.

The models are in slightly better agreement for next weekend with zonal flow taking over. This could still change depending on how the previously mentioned upper level low evolves but for now, it does seem most likely that rain chances will increase across the Northern Plains. This is supported by the ensembles as they show increasing chances for rain, up to a 30-50% chance for exceeding a tenth of an inch of rain. Sunday has the highest probabilities at this time. High temperatures look to remain warm but a little bit cooler than Thursday and Friday with highs only warming to the 70s and 80s.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 643 AM CDT Mon May 11 2026

VFR through the period. Southerly winds will strengthen through the day, with gusts of 25 to 35 mph expected, strongest near and west of I-29. LLWS will be possible tonight as a corridor of strong southwest winds about 1-3kft AGL moves through the area.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Frost Advisory until 9 AM CDT this morning for SDZ038>040- 053>056-061-062-067. MN...Frost Advisory until 9 AM CDT this morning for MNZ071-072-080- 081-089-090-097-098. IA...Frost Advisory until 9 AM CDT this morning for IAZ001>003- 012>014-021-022. NE...None.