South Dakota wakes up wrapped in gray, with headlights fading into thick fog and damp pavement already cooling fast. Visibility has dropped sharply across eastern counties, creating an uneasy start to a major holiday travel weekend as winter tightens its grip heading toward 2026.
According to the National Weather Service in Sioux Falls, a Dense Fog Advisory remains in effect this morning, with visibility falling to a quarter mile or less at times. Temperatures hover near freezing, which raises concern for slick spots on untreated roads, bridges, and overpasses as the fog thins.
The fog is expected to lift later this morning, but the quiet won’t last. Clouds hang tough today, with highs near 50 before colder air arrives. Light snow develops later today and into Sunday, with the best chance for accumulation by Sunday afternoon and evening. Snow amounts stay light, but gusty northwest winds could reach 40 to 45 mph, creating patchy blowing snow and reduced visibility on open highways like I-29 and I-90.
Sunday night into Monday brings a sharper punch of winter. Temperatures fall into the single digits, and wind chills dip below zero. Any moisture left on roads may freeze quickly, setting up classic flash-freeze conditions during peak end-of-year travel.
Looking ahead, conditions improve briefly Tuesday before another weak snow chance arrives midweek, brushing New Year’s Eve with cold, wintry air. Travelers should plan extra time, keep winter kits handy, and stay alert for rapidly changing road conditions.
Five-Day Outlook for Sioux Falls, SD
Today: Mostly cloudy, areas of fog early, high near 50.
Tonight: Light snow possible late, low around 17.
Sunday: Snow likely with blowing snow, high near 26.
Monday: Cold and partly sunny, high near 15.
Tuesday: Mostly sunny and cold, high near 35.
