NWS Forecast for Sioux City IA

National Weather Service Forecast for: Sioux City IA
Issued by: National Weather Service Sioux Falls, SD

Updated: 2:39 am CDT Aug 20, 2026

Overnight Patchy Dense Fog	Thursday Dense Fog then Sunny	Thursday Night Slight Chance T-storms then Mostly Clear	Friday Sunny	Friday Night Mostly Clear	Saturday Sunny	Saturday Night Partly Cloudy	Sunday Partly Sunny	Sunday Night Mostly Cloudy then Chance T-storms
Lo 60 °F	Hi 82 °F	Lo 64 °F	Hi 84 °F	Lo 62 °F	Hi 80 °F	Lo 59 °F	Hi 77 °F	Lo 62 °F

Hazardous Weather Outlook
Dense Fog Advisory

Overnight	Patchy dense fog. Otherwise, mostly clear, with a low around 60. Calm wind.
Thursday	Widespread dense fog, mainly before 8am. Otherwise, partly sunny, then gradually becoming sunny, with a high near 82. Light south wind becoming south southwest 5 to 10 mph in the morning.
Thursday Night	A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 11pm. Mostly clear, with a low around 64. Southwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 20%.
Friday	Sunny, with a high near 84. Calm wind becoming northwest around 5 mph.
Friday Night	Mostly clear, with a low around 62. Calm wind.
Saturday	Sunny, with a high near 80. Calm wind becoming northeast around 5 mph.
Saturday Night	Partly cloudy, with a low around 59.
Sunday	Partly sunny, with a high near 77.
Sunday Night	A 50 percent chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 62.
Monday	Partly sunny, with a high near 79.
Monday Night	Partly cloudy, with a low around 64.
Tuesday	Partly sunny, with a high near 82.
Tuesday Night	Partly cloudy, with a low around 63.
Wednesday	Partly sunny, with a high near 81.

Forecast from NOAA-NWS for Sioux City IA.