Sioux Center, Iowa climate: Normal weather by month, frost dates and records
Sioux Center's normal year runs from 9°F January nights to 85°F July afternoons, with 29.9 inches of precipitation and 35 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.9°C, January lows of −13°C, July highs of 29°C, 758 mm of precipitation a year.
- NOAA stationSioux Center (2 mi SE)
- Station IDUSC00137700
- Location43.06°N 96.15°W
- Elevation1,360 ft (415 m)
- Population8,675
On October 14, the normal high in Sioux Center is 65°F and the normal low 40°F, and the chance of measurable rain or snow is 24%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Sioux Center.
- Jan 27° 9°
- Feb 33° 14°
- Mar 46° 25°
- Apr 61° 36°
- May 73° 48°
- Jun 82° 59°
- Jul 85° 62°
- Aug 82° 60°
- Sep 77° 51°
- Oct 64° 39°
- Nov 46° 25°
- Dec 32° 15°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Sioux Center each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 9°F. The most precipitation falls in June (4.51 in), the least in January (0.67 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 27°F | 9°F | 18.4°F | 0.67 | 6.8 | 5 | <1 | 31 | 9 h 20 min |
| February | 33°F | 14°F | 23.4°F | 0.88 | 7.7 | 5 | <1 | 27 | 10 h 30 min |
| March | 46°F | 25°F | 35.7°F | 1.72 | 5.6 | 6 | <1 | 24 | 11 h 50 min |
| April | 61°F | 36°F | 48.7°F | 2.98 | 3.1 | 9 | <1 | 11 | 13 h 20 min |
| May | 73°F | 48°F | 60.8°F | 4.15 | 0.1 | 12 | 2 | 1 | 14 h 40 min |
| June | 82°F | 59°F | 70.7°F | 4.51 | 0.0 | 11 | 6 | <1 | 15 h 20 min |
| July | 85°F | 62°F | 73.3°F | 3.45 | 0.0 | 8 | 8 | <1 | 15 h |
| August | 82°F | 60°F | 70.9°F | 3.40 | 0.0 | 9 | 4 | <1 | 14 h |
| September | 77°F | 51°F | 64.2°F | 3.21 | 0.0 | 8 | 2 | 1 | 12 h 30 min |
| October | 64°F | 39°F | 51.1°F | 2.46 | 0.9 | 8 | <1 | 9 | 11 h 10 min |
| November | 46°F | 25°F | 35.6°F | 1.43 | 3.9 | 6 | <1 | 22 | 9 h 50 min |
| December | 32°F | 15°F | 23.0°F | 0.99 | 6.7 | 6 | <1 | 30 | 9 h |
| Year (annual) | 59°F | 37°F | 48.0°F | 29.85 | 34.8 | 93 | 23 | 154 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −3°C | −13°C | −7.6°C | 17 mm | 17 cm |
| February | 0°C | −10°C | −4.8°C | 22 mm | 20 cm |
| March | 8°C | −4°C | 2.1°C | 44 mm | 14 cm |
| April | 16°C | 2°C | 9.3°C | 76 mm | 8 cm |
| May | 23°C | 9°C | 16.0°C | 105 mm | 0 cm |
| June | 28°C | 15°C | 21.5°C | 115 mm | 0 cm |
| July | 29°C | 17°C | 22.9°C | 88 mm | 0 cm |
| August | 28°C | 15°C | 21.6°C | 86 mm | 0 cm |
| September | 25°C | 11°C | 17.9°C | 82 mm | 0 cm |
| October | 18°C | 4°C | 10.6°C | 62 mm | 2 cm |
| November | 8°C | −4°C | 2.0°C | 36 mm | 10 cm |
| December | 0°C | −10°C | −5.0°C | 25 mm | 17 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00137700; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Sioux Center?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, September has the fewest days with rain (8).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00137700.
When is the last frost in Sioux Center?
In Sioux Center, the last spring frost (32°F) comes after April 30 in half of years and after May 12 in one year in ten; the first autumn frost comes before October 3 in half of years and before September 19 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 301 year in 10 after May 12; 9 in 10 after April 17
- First autumn frost, half of years before
- October 31 year in 10 before September 19; 9 in 10 before October 18
NOAA puts the median frost-free season at 154 days, and the season without a hard freeze (28°F) at 175 days.
A hard freeze (28°F) comes after April 21 in half of springs and before October 14 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Sioux Center in zone 5a in ZIP code 51250, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Sioux Center's NOAA station is in zone 5a: the coldest night of a typical year reaches −19°F (28 complete years).
Frost dates for every NOAA station in Iowa · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00137700; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Sioux Center?
In a normal year in Sioux Center, 23 days a year reach 90°F (1 of them 100°F or more), 154 nights fall to 32°F or colder and 93 days bring measurable precipitation.
- Days at 90°F or more
- 23a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 154a normal year
- Days that stay below freezing
- 57high of 32°F or less
- Days with 0.01 inch of precipitation
- 93a normal year
- Days with 1 inch of snow or more
- 15a normal year
The highest temperature in this station's record (since 1899) is 109°F, on July 17, 1936; the lowest is −37°F, on January 12, 1912.
The wettest calendar year on that record is 2018, with 47.61 in; the snowiest season is 1982–83, with 73.2 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00137700; records: ACIS (NOAA Regional Climate Centers), station USC00137700. Records use complete months only; a month missing more than three days is left out.
How sunny is Sioux Center?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Sioux Center, 4.1 kWh per square metre a day. July is the sunniest month (85%) and May the cloudiest (71%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 75% | 2.0 |
| February | 79% | 3.1 |
| March | 72% | 3.9 |
| April | 71% | 5.0 |
| May | 71% | 5.6 |
| June | 77% | 6.4 |
| July | 85% | 6.7 |
| August | 81% | 5.5 |
| September | 79% | 4.4 |
| October | 74% | 3.0 |
| November | 74% | 2.1 |
| December | 71% | 1.6 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Sioux Center need?
A normal year in Sioux Center brings 6,993 heating degree days, 30% more than the median U.S. place (5,373), and 825 cooling degree days, 9% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,058 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,444 | 0 |
| February | 1,165 | 0 |
| March | 908 | 1 |
| April | 497 | 7 |
| May | 192 | 61 |
| June | 25 | 194 |
| July | 6 | 264 |
| August | 16 | 199 |
| September | 114 | 89 |
| October | 442 | 11 |
| November | 882 | 0 |
| December | 1,302 | 0 |
| Year (annual) | 6,993 | 825 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00137700. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Sioux Center been warmer than normal lately?
2025 averaged 50.4°F, 2.4°F above the 1991-2020 normal of 48.0°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 50.4°F | +2.4°F | 28.94 | 21.3 |
| 2022 | 48.4°F | +0.4°F | 14.90 | 11.0 |
| 2023 | 49.7°F | +1.7°F | 33.86 | 43.0 |
| 2024 | 51.5°F | +3.5°F | 34.52 | 17.4 |
| 2025 | 50.4°F | +2.4°F | 31.14 | 32.3 |
Over 86 complete years from 1902 to 2025, the station's annual mean temperature rose at a fitted 2.3°F per century (+0.13°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00137700; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Sioux Center's climate compare?
Sioux Center is warmer than 64 of the other 131 places with their own NOAA record in Iowa, and wetter than 6. Across the 7,247 U.S. stations with normals, its annual mean of 48.0°F is warmer than 32%.
In the Köppen classification computed from these normals, Sioux Center is Dfa: continental, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Sioux Center share this climate record?
4 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Orange City, IA6,547 people · 6 mi SE
- Hull, IA2,459 people · 9 mi N
- Alton, IA1,248 people · 9 mi SE
- Maurice, IA271 people · 6 mi S
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Sioux Center's climate
What is the coldest month in Sioux Center?
January, with a normal high of 27°F and a normal low of 9°F. The warmest is July (85°F by day, 62°F at night).
Does it snow in Sioux Center?
Yes: 35 inches in a normal year, falling on 18 days with 0.1 inch or more, the most in February (7.7 inches).
What is the rainiest month in Sioux Center?
June, with 4.51 in of precipitation in a normal year; the driest is January with 0.67 in.
What plant hardiness zone is Sioux Center in?
The USDA's 2023 map puts Sioux Center in zone 5a in ZIP code 51250, the nearest ZIP area. By the same method at Sioux Center's NOAA station, the coldest night of a typical year reaches −19°F (28 years, 1991-2020): zone 5a.
How late can frost come in Sioux Center?
In half of years the last 32°F night comes after April 30; in one year in ten it comes after May 12. Waiting until May 12 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Hawarden, IA17 miles from this station, 46.7°F a year
- Sheldon, IA17 miles from this station, 44.9°F a year
- Le Mars, IA19 miles from this station, 46.9°F a year
- Rock Rapids, IA26 miles from this station, 46.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made