textproduct: Sioux Falls

KEY MESSAGES

- Areas of frost are expected tonight especially north of I-90. Both a Freeze Warning and Frost Advisory will be in effect from 1 AM through 7 AM CDT for portions of the area. Make sure to cover/bring in any sensitive vegetation!

- Additional areas of frost will be possible by Thursday morning. However, slightly less cold temperatures and higher dew point depression may limit coverage/extent.

- After below normal temperatures through Wednesday, near to above normal temperatures will continue into the weekend with highs mainly in the 60s to 70s.

UPDATE

Issued at 841 PM CDT Tue May 5 2026

The forecast remains on track this evening with high probability (>80%) for freezing conditions for areas along and north of I-90 in southeast South Dakota and southwest Minnesota. The Freeze Warning in this area from 1 am until 7 am Wednesday morning is in good shape and no adjustments have been made. Areas to the south of I-90 there remains a little uncertainty as soundings indicate mid to upper level clouds hanging around through at least the first half of the overnight. If they linger longer they could slow or prevent surface temperatures from reaching freezing. In addition, large dew point depressions of 10-12 degrees F will likely prevent frost from forming at all. However, the projected low temperatures of 29-32 degrees F could still cause damage to sensitive vegetation. For these reasons, have decided to expanded the Frost Advisory to include Gregory, Charles Mix, Bon Homme, and Yankton counties in the existing advisory from 1 am until 7 am Wednesday morning. Temperatures rapidly increase after sunrise reaching highs of low to mid 50s, around 10 degrees below average for this time of year (mid 60s).

DISCUSSION

Issued at 120 PM CDT Tue May 5 2026

CURRENTS & TONIGHT: Another mild and breezy day continues! Taking a look across the area this afternoon, cloud cover continues to filter in as breezy northwesterly winds persists with gusts between 20-30 mph. While drier conditions this afternoon could promote some locally elevated fire concerns, greener fuels and milder temperatures will likely keep any fire danger risk in the low to moderate categories. Otherwise, the main concern tonight continues to be the potential for frost/freeze conditions. With the return of near to sub-freezing temperatures (26-32 degrees) and lighter surface winds tonight, areas of frost are expected to develop across most areas especially along and north of I-90. While there is still some uncertainty with coverage mainly due to 5-10 degree dew point depression, still thinking the conditions will do just enough for sensitive plants to be affected. As a result, have collaborated with neighboring offices to issue both a Freeze Warning and Frost advisory from 1 am to 7 am CDT. My thoughts are the warning is in place where confidence is highest on sub- freezing temperatures and widespread development with small dew point depressions. The advisory is in place for areas where patchy to scattered areas of frost are possible. With all this in mind, make sure to cover/bring in any sensitive vegetation!

WEDNESDAY-THURSDAY: Looking into the midweek, lingering cold air advection (CAA) and northwesterly surface winds will keep the milder stretch going through at least Wednesday night with highs in the low to upper 50s and overnight lows in the low to mid 30s. Similar to tonight, we could see additional chances for frost by Thursday morning. However, border-line temperatures and a higher dew point depression (8-12 degrees) will likely make coverage more patchy than scattered with the main focus being along our River Valleys. By Thursday, we'll start to trend warmer as a weakening ridge and a return to southwesterly to westerly flow brings an influx of warmer air to the area. This will lead to beautiful conditions as highs peak in the 60s to low 70s for the day with lighter winds.

THE WEEKEND ONWARDS: Heading into the extended period, an active pattern will once again return as continuous northwesterly flow aloft helps usher in multiple waves through our area. The strongest of which looks to arrive between Saturday to Sunday. While there is still some variability among long-range guidance, this still looks like our best chances (20%-30%) for areas along and south of I-90 to see rain. This is further agreed upon within ensemble guidance with most members showing a 30%-60% chance for at least measurable precipitation. Lastly, we'll continue our warming trend through Monday with highs mainly in the 60s to low 70s.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 621 PM CDT Tue May 5 2026

VFR conditions are expected to prevail this period. Breezy northwesterly winds will become light and variable overnight. Scattered to broken mid-level clouds will also persist through the period. After sunrise, winds become northwest around 10 kts. Winds continue to diurnally increase in the afternoon with gusts of 15-20 kts expected.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Frost Advisory from 1 AM to 7 AM CDT Wednesday for SDZ050- 063>071. Freeze Warning from 1 AM to 7 AM CDT Wednesday for SDZ038>040- 052>062. MN...Frost Advisory from 1 AM to 7 AM CDT Wednesday for MNZ090. Freeze Warning from 1 AM to 7 AM CDT Wednesday for MNZ071-072- 080-081-089-097-098. IA...Frost Advisory from 1 AM to 7 AM CDT Wednesday for IAZ001>003- 012>014-020>022. NE...None.