textproduct: Sioux Falls

KEY MESSAGES

- Localized fog will continue mainly in our waterways and low laying areas through mid-morning.

- Light to moderate showers will progress through areas along and south of I-90 as early as this afternoon. Accumulations of a 0.25" to 0.50" of an inch will be possible along the Missouri River Valley.

- After another day of below normal temperatures, the summer heat will return over the weekend with multiple days of highs in the 90s to low 100s ahead. Heat-realated headlines may be needed.

UPDATE

Issued at 328 AM CDT Thu Jul 23 2026

Taking a look across the area, quieter conditions persist as cloud cover continues to fill in west of Huron to Sioux Falls to Storm Lake, IA line. While the forecast still remains on track, a drearier day is ahead as cloud cover gradually spreads eastwards. However, with increasing southerly surface winds in place, expect highs to top out in the upper 70s to low 80s for the day. Shifting gears here, we'll see the return of light to moderate showers during the second half the day as another shortwave progresses through the area. While areas as far north as the I-90 corridor could see light accumulations, the highest accumulations are expected along the Missouri River Valley where a 0.25" to 0.50" of an inch will be possible. While flash flooding is not expected, deep warm cloud processes could lead to localized ponding if heavier showers persist over certain areas. Lastly, could see this activity persist across portion of the Highway-20 corridor and the lower Missouri River Valley through early Friday morning.

DISCUSSION

Issued at 142 PM CDT Wed Jul 22 2026

Light rain showers continue to drift through part of the area this afternoon. The abundant cloud cover has keep high temperatures on the cooler side with highs only warming to 60s and 70s. Rainfall amounts up to a few hundredths to a tenth or so remain mainly across south central South Dakota. Any chance for rain will come to an end by this evening, leaving partly cloudy to cloudy skies for the overnight hours. Despite the cloud cover, a surface high pushing through the area will keep light east/southeast flow going through the overnight timeframe, allowing for low temperatures to fall to the 50s to low 60s across the area.

Cloudy skies will persist through the day tomorrow, keeping high temperatures near to below average again in the 70s with a few spots reaching into the low 80s. Southerly return flow will pick up as the previously mentioned surface high departs to the southeast. Winds will still remain on the lighter side but a few gusts up to 20-25 mph is expected. Another shortwave trough will push through the forecast area, resulting in showers across the area once again. These showers look to be more widespread though remaining along and south of I-90 for the day. Forcing will be a bit stronger with this chance for rain along with very minor instability being present at or below 100 J/kg. This will bring overall higher rainfall amounts to locations along and south of a Chamberlain, South Dakota to Beresford, South Dakota to Storm Lake, Iowa where rainfall amounts between a quarter to a half an inch are possible (20-60%). Lighter amounts are expected north of this line. With the very minor instability in play, an isolated rumble of thunder is possible. This light rain will persist into the night before pushing southeast of the area by Friday morning.

Upper level ridging will begin to build over the central Plains on Friday, raising high temperatures back to the upper 70s, 80s, and low 90s. This trend will continue through the weekend as the thermal ridge slides eastwards. High temperatures look to return to above average with highs in the 90s to low 100s. The ensembles support this as they show high probabilities (60-100% chance) for high temperatures to exceed 90F along and west of I-90 over the weekend. Their probabilities drop to a 30-40% chance for highs to break 100F over the same area. The EFI also supports this as it shows 60-100% of its members suggesting anomalously warm temperatures this weekend and a shift of tails exceeding 1. Thus, will have to continue to monitor the potential for heat headlines being needed, especially as dew points look to remain in the 60s and 70s.

The heat looks to begin to wane on Monday as high temperatures look to only warm to the 90s. Highs will slightly cool into the middle of next week. With the forecast area being just on the northern gradient of the upper level ridge, ridge riding shortwaves could bring rain and perhaps storm chances back to the area. The ensembles only show low probabilities ranging from 0 to 30% so confidence is low in this potential as of now. Machine learning guidance also only shows a half a percent to about a 5% chance for severe storms Sunday through the middle of next week. Something to keep an eye on as we head into another hot and humid pattern.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1229 AM CDT Thu Jul 23 2026

VFR conditions expected for the majority of the period. Winds are light and variable. Patchy fog is possible just before sunrise this morning along water ways and low areas, mostly east of I-29. Fog is expected to burn off by mid morning.

Winds become southerly and increase after sunrise. Gusts of 15-25 kts are expected west of I-29, with the highest gusts over central South Dakota. Gusts to the east of I-29 should be 15 kts or less.

Storms begin to move in from the west this morning and will slowly make their way east-southeast through the end of the period. Severe weather is not anticipated but a few storms could produce lightning and brief, heavy downpours. The majority of the activity should remain along and south of I-90. KFSD has a low chance (30%) of periodic storms this afternoon and evening. KSUX has a 40-50% chance for storms this afternoon, with chances increasing to 70-80% in the late evening hours. Under storms ceilings and visibility may briefly be reduced to MVFR and possibly IFR status.

FSD WATCHES/WARNINGS/ADVISORIES

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