textproduct: Sioux Falls

KEY MESSAGES

- Light rain showers/sprinkles swing southeast prior to daybreak, mainly along and east of a De Smet to Sioux Falls to Spencer, Iowa line. Any accumulations will be minimal.

- Strong northwest winds continue this morning, with widespread gusts of 30-40 mph. Brief gusts of 45-55 mph may accompany the light showers early. Winds taper down Friday afternoon.

- Moderate to high (over 70%) chance of widespread frost tonight to early Saturday morning as temperatures fall into the lower to mid 30s.

- Freeze Warning has been issued for some areas along and east of Highway 59 where confidence is highest in a prolonged period of sub-freezing temperatures. Freeze Watch remains in effect where confidence is moderate-high that temperatures may briefly dip near 32F or below.

- Dry conditions and warmer temperatures return this weekend into early next week with highs back above normal.

UPDATE

Issued at 250 AM CDT Fri Oct 16 2026

Spotty light showers/sprinkles continue to swing southeast through Minnesota and eastern South Dakota early this morning, just moving into far northern Iowa as of 230 AM. Most locations will see a few sprinkles at best, but where low level moisture is a bit deeper, a more concentrated area of light showers will give portions of southwest Minnesota/northwest Iowa a few hundredths of an inch.

A narrow secondary band of cold advection is moving in along and just behind these showers/sprinkles. This combination could aid in briefly pulling gusts in excess of 45 mph to the surface through the pre-dawn hours. However, not seeing the stronger gusts remain persistent upstream across northeast SD/eastern ND. As such, will continue to hold off issuing a broader Wind Advisory this morning. Will continue to monitor upstream trends, though, and if stronger gusts become more persistent, may need to hoist a short-term wind headline into this morning.

Attention then turns to frost/freeze potential tonight into early Saturday morning. Previous shift expanded the Freeze Watch farther west which still seems reasonable. Main question in this area is whether the surface ridge will move east quickly enough to allow an uptick in south winds. This will support a non-diurnal rebound in temperatures late tonight and limit potential for sub-freezing temperatures. The NBM low temperatures remain colder than most raw guidance for temperatures overnight, with even the raw guidance showing a greater chance of sub-freezing temps in our eastern two tiers of counties where winds remain light through much of the overnight. For this reason, opted to join eastern neighbors in upgrading our far east to a Freeze Warning tonight into Saturday morning, while leaving the Freeze Watch in place where confidence is still lower farther west. It should be noted that the current Freeze Watch area, and even areas farther west, still have a very good chance at seeing frost development at some point during the night, so those with sensitive outdoor vegetation will likely need to take some precautions.

DISCUSSION

Issued at 231 PM CDT Thu Oct 15 2026

Rain is ending from northwest to southeast this afternoon as a northern stream upper trough and surface low drag a cold front through the region. At the same time the northern stream upper trough is merging into the southern stream trough responsible for the rain, deepening and strengthening the over all system. Strong winds have begun to develop in response to the tightening SPG and a strong push of CAA. Widespread gusts of 30 to 40 mph are expected. The strongest winds will be located over central South Dakota where gusts to 50 mph are possible. A Wind Advisory is in effect for this area until 4 am Friday morning. The strongest winds will move east overnight with the upper trough but should remain under advisory criteria at 35 to 40 mph. Thanks to the mixy winds and lingering clouds overnight lows tonight will remain in the upper 30s to low 40s.

Early Friday morning there is a chance for additional light, scattered rain showers as moisture wraps around the surface low located over Minnesota. This combined with a second strong push of CAA will result in the LLJ increasing to 50+ kts over east central South Dakota and southwest Minnesota. An area of wind gusts up to 45 mph may be possible in southwest Minnesota. At this time, confidence in winds meeting advisory level criteria are too low to issue a headline. But this will need to be monitored through Friday morning. Winds gradually taper off through Friday afternoon. Highs for Friday will be below average for this time of year (average is low 60s) in the upper 40s to low 50s. Clouds break up through the afternoon and skies will be clear overnight with nearly calm winds. Radiational cooling will allow lows to fall into the mid to low 30s. Areas along and east of I-29 are likely to see temperatures fall to 30 degrees, therefore have issued a Freeze Watch from late Friday night into Saturday morning. Precautions are recommended for sensitive outdoor plants. Areas to the west of I-29 may have the potential for frost development, but confidence was too low at this time to issue a Frost Advisory.

An upper ridge builds into the area for the weekend. Winds turn southerly and WAA will boost our highs back into the upper 50s to mid 60s. Lows will be in the 40s. Dry and warmer than average conditions continue Sunday through the middle part of next week. Highs will warm from the the mid 60s Sunday and Monday into the low 70s Tuesday and Wednesday. Chances for rain return for the second half of next week.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1045 PM CDT Thu Oct 15 2026

Lower VFR and MVFR stratus continue overnight into mid to late Friday morning. Scattered showers are expected along and northeast of a KHON/KFSD/KSPW line, but confidence is too low in coverage for inclusion at KHON/KFSD. These could bring some lower MVFR stratus. Showers exit just after daybreak. Skies clear through the day Friday, with VFR conditions for the afternoon into the night.

Main focus of the period is on the strong northwesterly winds through the overnight hours. Guidance is generally split on the timing of the stronger gusts overnight and into Friday morning, likely due to LLJ timing differences between models. Have kept winds/gusts fairly similar to previous, with a shift in the stronger winds for KSUX into the later morning Friday. Gusts 30 to 35 knots are expected, with strongest gusts into the early overnight and across south central SD. May also see some stronger gusts into the higher elevations of the Buffalo Ridge overnight, around or above 35 knots. Winds taper down through the day on Friday, becoming light and variable in the evening.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Freeze Watch from late tonight through Saturday morning for SDZ039-040-054>056-060>062-065>071. Wind Advisory until 4 AM CDT early this morning for SDZ050-057- 063. MN...Freeze Watch from late tonight through Saturday morning for MNZ071-072-080-097-098. Freeze Warning from 1 AM to 9 AM CDT Saturday for MNZ081-089- 090. IA...Freeze Watch from late tonight through Saturday morning for IAZ001-012-020-031. Freeze Warning from 1 AM to 9 AM CDT Saturday for IAZ002-003- 013-014-021-022-032. NE...Freeze Watch from late tonight through Saturday morning for NEZ013-014.