Winterset, Iowa climate: Normal weather by month, frost dates and records
Winterset's normal year runs from 10°F January nights to 84°F July afternoons, with 34.8 inches of precipitation and 31 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.9°C, January lows of −12°C, July highs of 29°C, 884 mm of precipitation a year.
- NOAA stationWinterset (1 mi S)
- Station IDUSC00139132
- Location41.31°N 94.02°W
- Elevation1,100 ft (335 m)
- Population5,421
On October 23, the normal high in Winterset is 60°F and the normal low 35°F, and the chance of measurable rain or snow is 23%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Winterset.
- Jan 30° 10°
- Feb 35° 13°
- Mar 48° 25°
- Apr 61° 35°
- May 71° 48°
- Jun 80° 58°
- Jul 84° 62°
- Aug 82° 59°
- Sep 76° 51°
- Oct 63° 38°
- Nov 48° 26°
- Dec 35° 16°
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 Winterset each month?
July is the warmest month, with normal highs of 84°F; January the coldest, with normal lows of 10°F. The most precipitation falls in May (4.99 in), the least in January (0.78 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 30°F | 10°F | 19.9°F | 0.78 | 7.3 | 5 | <1 | 30 | 9 h 30 min |
| February | 35°F | 13°F | 24.0°F | 1.28 | 8.3 | 6 | <1 | 25 | 10 h 40 min |
| March | 48°F | 25°F | 36.2°F | 2.12 | 4.7 | 7 | <1 | 22 | 11 h 50 min |
| April | 61°F | 35°F | 48.0°F | 3.59 | 0.8 | 10 | <1 | 9 | 13 h 20 min |
| May | 71°F | 48°F | 59.4°F | 4.99 | 0.1 | 12 | <1 | 1 | 14 h 30 min |
| June | 80°F | 58°F | 69.2°F | 4.64 | 0.0 | 10 | 2 | <1 | 15 h 10 min |
| July | 84°F | 62°F | 73.0°F | 4.10 | 0.0 | 10 | 6 | <1 | 14 h 50 min |
| August | 82°F | 59°F | 70.9°F | 3.62 | 0.0 | 9 | 5 | <1 | 13 h 50 min |
| September | 76°F | 51°F | 63.1°F | 3.60 | 0.0 | 7 | 2 | 1 | 12 h 30 min |
| October | 63°F | 38°F | 50.8°F | 2.88 | 0.9 | 8 | <1 | 8 | 11 h 10 min |
| November | 48°F | 26°F | 37.1°F | 1.96 | 2.7 | 6 | <1 | 20 | 9 h 50 min |
| December | 35°F | 16°F | 25.5°F | 1.23 | 5.9 | 6 | <1 | 29 | 9 h 10 min |
| Year (annual) | 59°F | 37°F | 48.1°F | 34.79 | 30.7 | 96 | 15 | 145 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −12°C | −6.7°C | 20 mm | 19 cm |
| February | 2°C | −10°C | −4.4°C | 33 mm | 21 cm |
| March | 9°C | −4°C | 2.3°C | 54 mm | 12 cm |
| April | 16°C | 2°C | 8.9°C | 91 mm | 2 cm |
| May | 22°C | 9°C | 15.2°C | 127 mm | 0 cm |
| June | 27°C | 15°C | 20.7°C | 118 mm | 0 cm |
| July | 29°C | 17°C | 22.8°C | 104 mm | 0 cm |
| August | 28°C | 15°C | 21.6°C | 92 mm | 0 cm |
| September | 24°C | 10°C | 17.3°C | 91 mm | 0 cm |
| October | 17°C | 3°C | 10.4°C | 73 mm | 2 cm |
| November | 9°C | −3°C | 2.8°C | 50 mm | 7 cm |
| December | 2°C | −9°C | −3.6°C | 31 mm | 15 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00139132; 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 Winterset?
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 (7).
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 USC00139132.
When is the last frost in Winterset?
In Winterset, the last spring frost (32°F) comes after April 30 in half of years and after May 11 in one year in ten; the first autumn frost comes before October 3 in half of years and before September 20 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 11; 9 in 10 after April 17
- First autumn frost, half of years before
- October 31 year in 10 before September 20; 9 in 10 before October 20
NOAA puts the median frost-free season at 157 days, and the season without a hard freeze (28°F) at 178 days.
A hard freeze (28°F) comes after April 20 in half of springs and before October 15 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Winterset in zone 5b in ZIP code 50273, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Winterset's NOAA station is in zone 5a: the coldest night of a typical year reaches −15°F (23 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Iowa · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00139132; 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 Winterset?
In a normal year in Winterset, 15 days a year reach 90°F, 145 nights fall to 32°F or colder and 96 days bring measurable precipitation.
- Days at 90°F or more
- 15a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 145a normal year
- Days that stay below freezing
- 49high of 32°F or less
- Days with 0.01 inch of precipitation
- 96a normal year
- Days with 1 inch of snow or more
- 12a normal year
The highest temperature in this station's record (since 1893) is 112°F, on August 8, 1934; the lowest is −35°F, on March 1, 1962.
The wettest calendar year on that record is 1993, with 48.91 in; the snowiest season is 2007–08, with 60.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00139132; records: ACIS (NOAA Regional Climate Centers), station USC00139132. Records use complete months only; a month missing more than three days is left out.
How sunny is Winterset?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Winterset, 4.1 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (69%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 70% | 2.0 |
| February | 75% | 3.1 |
| March | 70% | 3.9 |
| April | 70% | 4.9 |
| May | 72% | 5.7 |
| June | 78% | 6.3 |
| July | 82% | 6.4 |
| August | 80% | 5.6 |
| September | 80% | 4.6 |
| October | 74% | 3.2 |
| November | 73% | 2.2 |
| December | 69% | 1.7 |
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 Winterset need?
A normal year in Winterset brings 6,870 heating degree days, 28% more than the median U.S. place (5,373), and 738 cooling degree days, 19% 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 2,919 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,400 | 0 |
| February | 1,148 | 0 |
| March | 893 | 1 |
| April | 515 | 3 |
| May | 213 | 40 |
| June | 32 | 157 |
| July | 7 | 255 |
| August | 18 | 199 |
| September | 132 | 75 |
| October | 450 | 10 |
| November | 839 | 0 |
| December | 1,224 | 0 |
| Year (annual) | 6,870 | 738 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00139132. 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 Winterset been warmer than normal lately?
2023 averaged 51.5°F, 3.4°F above the 1991-2020 normal of 48.1°F.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2023 | 51.5°F | +3.4°F | 28.58 | – |
Over 89 complete years from 1895 to 2023, the station's annual mean temperature rose at a fitted 0.6°F per century (+0.03°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00139132; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Winterset's climate compare?
Winterset is warmer than 65 of the other 131 places with their own NOAA record in Iowa, and wetter than 36. Across the 7,247 U.S. stations with normals, its annual mean of 48.1°F is warmer than 32%.
In the Köppen classification computed from these normals, Winterset 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 Winterset share this climate record?
8 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.
- Van Meter, IA1,840 people · 15 mi N
- Earlham, IA1,411 people · 14 mi NW
- De Soto, IA937 people · 15 mi N
- Truro, IA515 people · 11 mi SE
- Lorimor, IA377 people · 13 mi S
- Patterson, IA176 people · 8 mi E
- East Peru, IA119 people · 8 mi SE
- Macksburg, IA103 people · 11 mi SW
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 Winterset's climate
What is the coldest month in Winterset?
January, with a normal high of 30°F and a normal low of 10°F. The warmest is July (84°F by day, 62°F at night).
Does it snow in Winterset?
Yes: 31 inches in a normal year, falling on 16 days with 0.1 inch or more, the most in February (8.3 inches).
What is the rainiest month in Winterset?
May, with 4.99 in of precipitation in a normal year; the driest is January with 0.78 in.
What plant hardiness zone is Winterset in?
The USDA's 2023 map puts Winterset in zone 5b in ZIP code 50273, the nearest ZIP area. By the same method at Winterset's NOAA station, the coldest night of a typical year reaches −15°F (23 years, 1991-2020): zone 5a.
How late can frost come in Winterset?
In half of years the last 32°F night comes after April 30; in one year in ten it comes after May 11. Waiting until May 11 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Indianola, IA19 miles from this station, 49.9°F a year
- Greenfield, IA22 miles from this station, 49.1°F a year
- Des Moines, IA24 miles from this station, 50.9°F a year
- Osceola, IA25 miles from this station, 49.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made