Spencer, Iowa climate: Normal weather by month, frost dates and records
Spencer's normal year runs from 8°F January nights to 85°F July afternoons, with 26.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.2°C, January lows of −13°C, July highs of 29°C, 681 mm of precipitation a year.
- NOAA stationSpencer Municipal Airport
- Station IDUSW00014972
- Location43.16°N 95.20°W
- Elevation1,338 ft (408 m)
- From the center3 miles
- Population11,418
On October 23, the normal high in Spencer is 57°F and the normal low 34°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 Spencer.
- Jan 26° 8°
- Feb 30° 13°
- Mar 44° 25°
- Apr 59° 36°
- May 71° 48°
- Jun 81° 59°
- Jul 85° 62°
- Aug 82° 59°
- Sep 76° 50°
- Oct 61° 37°
- Nov 45° 25°
- Dec 31° 14°
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 Spencer each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 8°F. The most precipitation falls in June (4.01 in), the least in January (0.25 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 26°F | 8°F | 16.9°F | 0.25 | 4 | <1 | 31 | 9 h 20 min |
| February | 30°F | 13°F | 21.4°F | 0.43 | 4 | <1 | 27 | 10 h 30 min |
| March | 44°F | 25°F | 34.2°F | 1.44 | 6 | <1 | 25 | 11 h 50 min |
| April | 59°F | 36°F | 47.2°F | 2.82 | 10 | <1 | 12 | 13 h 20 min |
| May | 71°F | 48°F | 59.4°F | 3.83 | 13 | 1 | 2 | 14 h 40 min |
| June | 81°F | 59°F | 69.8°F | 4.01 | 12 | 4 | <1 | 15 h 20 min |
| July | 85°F | 62°F | 73.4°F | 3.84 | 9 | 7 | <1 | 15 h 10 min |
| August | 82°F | 59°F | 70.6°F | 3.29 | 11 | 3 | <1 | 14 h |
| September | 76°F | 50°F | 63.0°F | 3.21 | 9 | 2 | 1 | 12 h 30 min |
| October | 61°F | 37°F | 49.4°F | 2.22 | 8 | <1 | 11 | 11 h 10 min |
| November | 45°F | 25°F | 34.6°F | 1.07 | 5 | <1 | 24 | 9 h 50 min |
| December | 31°F | 14°F | 22.2°F | 0.42 | 5 | <1 | 30 | 9 h |
| Year (annual) | 57°F | 36°F | 46.8°F | 26.83 | 97 | 19 | 163 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −3°C | −13°C | −8.4°C | 6 mm |
| February | −1°C | −11°C | −5.9°C | 11 mm |
| March | 6°C | −4°C | 1.2°C | 37 mm |
| April | 15°C | 2°C | 8.4°C | 72 mm |
| May | 22°C | 9°C | 15.2°C | 97 mm |
| June | 27°C | 15°C | 21.0°C | 102 mm |
| July | 29°C | 17°C | 23.0°C | 98 mm |
| August | 28°C | 15°C | 21.4°C | 84 mm |
| September | 24°C | 10°C | 17.2°C | 82 mm |
| October | 16°C | 3°C | 9.7°C | 56 mm |
| November | 7°C | −4°C | 1.4°C | 27 mm |
| December | −1°C | −10°C | −5.4°C | 11 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Spencer's own co-op station Spencer (1 mi N) does: 43 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014972; 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 Spencer?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, July has the fewest days with rain (9).
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 USW00014972.
When is the last frost in Spencer?
In Spencer, the last spring frost (32°F) comes after May 2 in half of years and after May 15 in one year in ten; the first autumn frost comes before October 2 in half of years and before September 18 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
- May 21 year in 10 after May 15; 9 in 10 after April 17
- First autumn frost, half of years before
- October 21 year in 10 before September 18; 9 in 10 before October 16
NOAA puts the median frost-free season at 154 days, and the season without a hard freeze (28°F) at 172 days.
A hard freeze (28°F) comes after April 22 in half of springs and before October 12 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Spencer in zone 5a in ZIP code 51301, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Spencer's NOAA station is in zone 4b: the coldest night of a typical year reaches −21°F (24 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 USW00014972; 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 Spencer?
In a normal year in Spencer, 19 days a year reach 90°F, 163 nights fall to 32°F or colder and 97 days bring measurable precipitation.
- Days at 90°F or more
- 19a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 163a normal year
- Days that stay below freezing
- 65high of 32°F or less
- Days with 0.01 inch of precipitation
- 97a normal year
The highest temperature in Spencer's official record (kept by the National Weather Service since 1895) is 113°F, on July 17, 1936; the lowest is −38°F, on January 12, 1912.
The wettest calendar year on that record is 1951, with 42.51 in; the snowiest season is 1961–62, with 81.9 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00014972; records: ACIS (NOAA Regional Climate Centers), NWS threaded record SPWthr. Records use complete months only; a month missing more than three days is left out.
How sunny is Spencer?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Spencer, 4.1 kWh per square metre a day. July is the sunniest month (84%) and December the cloudiest (69%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 74% | 2.0 |
| February | 79% | 3.1 |
| March | 72% | 3.9 |
| April | 70% | 4.9 |
| May | 70% | 5.6 |
| June | 76% | 6.3 |
| July | 84% | 6.6 |
| August | 81% | 5.5 |
| September | 79% | 4.4 |
| October | 73% | 3.0 |
| November | 72% | 2.0 |
| December | 69% | 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 Spencer need?
A normal year in Spencer brings 7,353 heating degree days, 37% more than the median U.S. place (5,373), and 774 cooling degree days, 15% 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 2,898 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,489 | 0 |
| February | 1,219 | 0 |
| March | 955 | 0 |
| April | 538 | 4 |
| May | 221 | 47 |
| June | 32 | 176 |
| July | 7 | 267 |
| August | 18 | 190 |
| September | 140 | 80 |
| October | 494 | 9 |
| November | 911 | 0 |
| December | 1,328 | 0 |
| Year (annual) | 7,353 | 774 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014972. 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 Spencer been warmer than normal lately?
2025 averaged 48.0°F, 1.2°F above the 1991-2020 normal of 46.8°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 48.8°F | +2.0°F | – |
| 2022 | 46.8°F | at normal | 21.63 |
| 2023 | 49.2°F | +2.4°F | 25.42 |
| 2024 | 50.9°F | +4.1°F | 34.81 |
| 2025 | 48.0°F | +1.2°F | 27.91 |
Source: observed years: ACIS, station USW00014972. A year counts only with all twelve months complete.
How does Spencer's climate compare?
Spencer is warmer than 38 of the other 131 places with their own NOAA record in Iowa, and wetter than 0. Across the 7,247 U.S. stations with normals, its annual mean of 46.8°F is warmer than 27%.
In the Köppen classification computed from these normals, Spencer is Dwa: continental, dry-winter, 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 Spencer 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.
- Everly, IA570 people · 6 mi W
- Royal, IA379 people · 8 mi SW
- Fostoria, IA229 people · 6 mi NE
- Dickens, IA146 people · 9 mi E
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Spencer's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Spencer. This page uses Spencer Municipal Airport; the other differs by site and elevation:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Spencer (1 mi N) USC00137844 | 1 mi N | 1,326 ft | 46.1°F | 7°F | 84°F | 31.0 | 43 | May 1 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Spencer's climate
What is the coldest month in Spencer?
January, with a normal high of 26°F and a normal low of 8°F. The warmest is July (85°F by day, 62°F at night).
Does it snow in Spencer?
Yes. NOAA publishes no 1991-2020 snowfall normal for Spencer's NOAA station; Spencer's own co-op station Spencer (1 mi N) records 43 inches of snow in a normal year.
What is the rainiest month in Spencer?
June, with 4.01 in of precipitation in a normal year; the driest is January with 0.25 in.
What plant hardiness zone is Spencer in?
The USDA's 2023 map puts Spencer in zone 5a in ZIP code 51301, the nearest ZIP area. By the same method at Spencer's NOAA station, the coldest night of a typical year reaches −21°F (24 years, 1991-2020): zone 4b.
How late can frost come in Spencer?
In half of years the last 32°F night comes after May 2; in one year in ten it comes after May 15. Waiting until May 15 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Milford, IA15 miles from this station, 46.0°F a year
- Spirit Lake, IA18 miles from this station, 45.7°F a year
- Sioux Rapids, IA20 miles from this station, 46.4°F a year
- Lake Park, IA21 miles from this station, 46.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made