Sioux City Climate by Month
Sioux City, Iowa, United States
Hot summers and freezing winters, with rain spread through the year.
Sioux City has hot summers and freezing winters, with rain spread through the year. Expect highs of 87°F (31°C) in July and 30°F (-1°C) in January, with the coldest nights (January) near 11°F (-12°C). It gets 27 in (691 mm) of rain a year, spread across the months.
- Warmest month
- 87°F(31°C)
- Average high, July
- Coldest nights
- 11°F(-12°C)
- Average low, January
- Rain per year
- 27 in(691 mm)
- No clear rainy season
- Humidity
- 70%
- Sunniest: July
Best and worst months in Sioux City
Best for weatherThe most comfortable weather comes in May and September, with highs around 75°F (24°C) and about 3.4 in (86 mm) of rain a month.
Least pleasantDecember and January are the least pleasant; January is the coldest, with highs of only 30°F (-1°C).
Comfort combines how close the afternoon high is to 75°F (24°C) with how much rain falls and how humid it is. See where the weather is best in September.
Temperature and rain through the year
Highs and lows (°F)
Average highAverage low
Rain (in per month)
Sioux City weather by month
| Month | High | Low | Rain | Humidity | Sun |
|---|---|---|---|---|---|
| JanJanuary | 30°F(-1°C) | 11°F(-12°C) | 0.6 in(15 mm) | 79% | 1.6 |
| FebFebruary | 35°F(2°C) | 15°F(-9°C) | 0.7 in(19 mm) | 87% | 2.6 |
| MarMarch | 49°F(9°C) | 27°F(-3°C) | 1.7 in(42 mm) | 65% | 3.8 |
| AprApril | 62°F(17°C) | 38°F(3°C) | 3.0 in(76 mm) | 57% | 4.7 |
| MayMayBest | 73°F(23°C) | 49°F(10°C) | 4.2 in(106 mm) | 60% | 5.4 |
| JunJune | 83°F(28°C) | 60°F(16°C) | 4.5 in(114 mm) | 65% | 6.1 |
| JulJuly | 87°F(31°C) | 65°F(18°C) | 2.9 in(73 mm) | 72% | 6.4 |
| AugAugust | 85°F(29°C) | 62°F(17°C) | 3.2 in(82 mm) | 71% | 5.5 |
| SepSeptemberBest | 78°F(25°C) | 53°F(12°C) | 2.6 in(66 mm) | 66% | 4.6 |
| OctOctober | 64°F(18°C) | 40°F(4°C) | 2.0 in(51 mm) | 61% | 3.0 |
| NovNovember | 47°F(8°C) | 26°F(-3°C) | 1.0 in(26 mm) | 68% | 2.0 |
| DecDecember | 33°F(1°C) | 15°F(-9°C) | 0.8 in(21 mm) | 89% | 1.5 |
1991–2020 averages. Sun is solar radiation in kWh/m² per day. Highlighted: the most comfortable months.
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