textproduct: Sioux Falls

KEY MESSAGES

- Patchy fog may build into the Buffalo Ridge tonight. Some uncertainty remains, but be prepared to follow the necessary safety precautions should it develop.

- Extreme Temperature Ranges Monday: A stalled cold front will create a sharp contract in temperatures Monday. 50s are possible near Huron, while the 80s will be likely near Sioux City/Storm Lake.

- Dry Mid-Week With Rain Returning Thursday: Near normal temperatures and dry conditions likely through Wednesday. Scattered rain by Thursday with a 60% probability of greater than 0.10" of rain by Friday.

- Turning Colder: Temperatures into next weekend fall below normal into the 50s.

UPDATE

Issued at 845 PM CDT Sun Oct 11 2026

A cold front continues to push through the forecast area this evening. The front is currently visible on satellite imagery and may begin to slow down soon before stalling for the rest of the night. This will lead to a wide range for low temperatures as locations towards central and south central South Dakota look to see lows fall to the 50s while areas ahead of the front, mainly across northwest Iowa, will see mild lows in the 60s. Low level stratus is also beginning to push into the area from the west. While the stratus should stay elevated, some models suggest that patchy fog could develop along the buffalo ridge in southwest Minnesota. There is currently some patchy fog along the ridge up into northeast South Dakota, so will watch trends in this fogs potential through the rest of the night.

Monday will be the last day with highs in the 80s for parts of southwest Minnesota, far northeast Nebraska, far southeast South Dakota, and northwest Iowa as the previously mentioned front will fully push through the forecast area. Locations to the west of the boundary will see cooler highs, only warming to the 60s and 70s. This will result in a large temperature gradient across the forecast area. There still remains the chance (15-20%) for light rain showers primarily in the morning before any chance for light rain diminishes for the afternoon and evening timeframes. Low temperatures will be near seasonable to above average in the 40s and 50s.

Surface ridging will push into the Northern Plains on Tuesday, keeping dry conditions for the day. This will provide northerly winds for the day, keeping high temperatures closer to seasonable in the 60s to perhaps low 70s.

DISCUSSION

Issued at 1242 PM CDT Sun Oct 11 2026

THIS AFTERNOON: Another very warm day across the Tri-State area as temperatures continue to rise into the 80s. Further west however, a frontal boundary has stalled from Gregory to near Huron and north of Watertown. Northwesterly drainage winds are doing what they like to do and keeping temperatures cooler with considerable stratus through central and northern South Dakota. This front will stay nearly stationary into late afternoon, perhaps sliding a bit further southeast into the MO River valley. Temperatures will likely fall short of records in most locations, however gusty winds greater than 25 mph in NW Iowa could promote elevated agricultural related fire risks to sunset.

TONIGHT: My confidence is rising that the cold front will continue slipping southeast through the overnight hours, though just how far southeast is still in question. Should the front reach into NW Iowa and NE Nebraska, then a significant amount of cooler air may drain southeast knocking temperatures further into the upper 40s to lower 50s. Anticipating stratus to reform late tonight, especially in areas from Gregory to Brookings and Marshall where cool air will continue to drain.

MONDAY: We're likely to start the day with quite a bit of stratus in the CWA, potentially as far SE as Sioux Falls. A mid-lvl shortwave tracking through the Dakotas mid-morning to mid-day will accomplish two tasks, lifting the cold front very slightly back northwest, but also pinning in cooler and moist air in the drainage flow on the backside of the front. The end result may be an extreme temperature gradient of the 80s in Sioux City and Storm Lake/Spencer, to the 50s in Huron. Latest NBM will not catch these mesoscale temperature gradients, so have adjusted and blended in higher resolution guidance. However the gradient may still be more defined than the current forecast suggests. While moisture is lacking aloft, a few sprinkles to light rain showers could develop through central and northeastern SODAK in the day. Have also manually pushed up stratus through mid-day west of I-29.

MONDAY NIGHT: Northwest winds continue through the overnight hours into Tuesday as quite a bit of cooler Canadian air filters southeast This will push overnight lows into the 40s in several areas with some questions on cloud cover potential lingering.

TUESDAY-WEDNESDAY: Latest forecast guidance continues to trend drier with precipitation chances during the middle of the week. The amplitude of mid-lvl ridging through the Central and Southern Plains may be strong enough to prevent any cut off energy in the Four Corners from moving eastward as quick as guidance hinted yesterday. The end result will be dry conditions Tuesday and Wednesday with highs near or even slightly above seasonal normals.

THURSDAY-SATURDAY: The cutoff energy in the Four Corners may eventually phase with a secondary northern stream trough crossing the Canadian Rockies by Thursday. Increasing warm advection and moisture return ahead of this trough combined with mid-lvl dPVA may result in the development of scattered rain by Thursday. Latest ensemble probabilities continue to suggest light rain amounts with 60-70% probabilities of >0.10", but only 30% probabilities of more than 0.50". High pressure will quickly swing southeast into the Plains for Friday and the upcoming weekend. Temperatures for at least a couple days may cool below seasonal normals, but only slightly.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1050 PM CDT Sun Oct 11 2026

Still seeing MVFR/IFR stratus push into the area from the west. The stratus now completely covers KHON and will persist through the night. Think the stratus will slowly expand southeastwards but not quite make it to KFSD. Do think that the potential for stratus and fog has increased for the Buffalo Ridge area in southwest Minnesota and parts of east central South Dakota. Low level wind shear (LLWS) remains on track to strengthen over the next few hours across northwest Iowa, including KSUX, and persist through the night. The stratus, and fog, look to lift through the morning hours. Though could see low level stratus persist through a large part of the day, especially at KHON. Winds will turn northwesterly throughout the day with gusts up to about 15 to 25 knots expected. The winds will weaken tomorrow evening to end the TAF period.

FSD WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None. IA...None. NE...None.