Allison, Iowa climate: Normal weather by month, frost dates and records
Allison's normal year runs from 8°F January nights to 83°F July afternoons, with 35.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.2°C, January lows of −14°C, July highs of 28°C, 899 mm of precipitation a year.
- NOAA stationAllison
- Station IDUSC00130157
- Location42.75°N 92.80°W
- Elevation1,038 ft (316 m)
- From the centerunder 1 mile
- Population937
On October 23, the normal high in Allison is 57°F and the normal low 36°F, and the chance of measurable rain or snow is 21%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Allison.
- Jan 25° 8°
- Feb 29° 12°
- Mar 43° 24°
- Apr 59° 36°
- May 70° 49°
- Jun 80° 59°
- Jul 83° 63°
- Aug 80° 60°
- Sep 74° 51°
- Oct 61° 39°
- Nov 44° 25°
- Dec 31° 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 Allison each month?
July is the warmest month, with normal highs of 83°F; January the coldest, with normal lows of 8°F. The most precipitation falls in June (5.46 in), the least in January (0.94 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 25°F | 8°F | 16.2°F | 0.94 | 5 | <1 | 31 | 9 h 20 min |
| February | 29°F | 12°F | 20.5°F | 1.04 | 5 | <1 | 27 | 10 h 30 min |
| March | 43°F | 24°F | 33.7°F | 1.79 | 7 | <1 | 23 | 11 h 50 min |
| April | 59°F | 36°F | 47.2°F | 3.81 | 9 | <1 | 10 | 13 h 20 min |
| May | 70°F | 49°F | 59.4°F | 5.13 | 12 | 1 | 1 | 14 h 40 min |
| June | 80°F | 59°F | 69.6°F | 5.46 | 11 | 3 | <1 | 15 h 20 min |
| July | 83°F | 63°F | 72.7°F | 4.20 | 8 | 5 | <1 | 15 h |
| August | 80°F | 60°F | 70.3°F | 4.04 | 8 | 2 | <1 | 14 h |
| September | 74°F | 51°F | 62.8°F | 3.37 | 8 | 1 | <1 | 12 h 30 min |
| October | 61°F | 39°F | 50.0°F | 2.51 | 7 | <1 | 8 | 11 h 10 min |
| November | 44°F | 25°F | 34.9°F | 1.76 | 5 | <1 | 22 | 9 h 50 min |
| December | 31°F | 15°F | 22.6°F | 1.35 | 6 | <1 | 30 | 9 h |
| Year (annual) | 57°F | 37°F | 46.7°F | 35.40 | 90 | 12 | 150 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −4°C | −14°C | −8.8°C | 24 mm |
| February | −1°C | −11°C | −6.4°C | 26 mm |
| March | 6°C | −4°C | 0.9°C | 45 mm |
| April | 15°C | 2°C | 8.4°C | 97 mm |
| May | 21°C | 9°C | 15.2°C | 130 mm |
| June | 27°C | 15°C | 20.9°C | 139 mm |
| July | 28°C | 17°C | 22.6°C | 107 mm |
| August | 27°C | 16°C | 21.3°C | 103 mm |
| September | 24°C | 11°C | 17.1°C | 86 mm |
| October | 16°C | 4°C | 10.0°C | 64 mm |
| November | 7°C | −4°C | 1.6°C | 45 mm |
| December | −1°C | −10°C | −5.2°C | 34 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Charles City (22 miles away), gets 38 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00130157; 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 Allison?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, August 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 USC00130157.
When is the last frost in Allison?
In Allison, the last spring frost (32°F) comes after April 27 in half of years and after May 8 in one year in ten; the first autumn frost comes before October 8 in half of years and before September 24 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 271 year in 10 after May 8; 9 in 10 after April 12
- First autumn frost, half of years before
- October 81 year in 10 before September 24; 9 in 10 before October 22
NOAA puts the median frost-free season at 165 days, and the season without a hard freeze (28°F) at 185 days.
A hard freeze (28°F) comes after April 16 in half of springs and before October 20 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Allison in zone 5a in ZIP code 50602, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Allison's NOAA station is in zone 5a: the coldest night of a typical year reaches −17°F (30 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 USC00130157; 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 Allison?
In a normal year in Allison, 12 days a year reach 90°F, 150 nights fall to 32°F or colder and 90 days bring measurable precipitation.
- Days at 90°F or more
- 12a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 150a normal year
- Days that stay below freezing
- 64high of 32°F or less
- Days with 0.01 inch of precipitation
- 90a normal year
The highest temperature in this station's record (since 1914) is 109°F, on July 14, 1936; the lowest is −31°F, on February 2, 1996.
The wettest calendar year on that record is 2018, with 50.33 in; the snowiest season is 1961–62, with 71.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00130157; records: ACIS (NOAA Regional Climate Centers), station USC00130157. Records use complete months only; a month missing more than three days is left out.
How sunny is Allison?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Allison, 4.0 kWh per square metre a day. July is the sunniest month (81%) and December the cloudiest (66%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 70% | 1.9 |
| February | 76% | 3.0 |
| March | 72% | 3.9 |
| April | 69% | 4.8 |
| May | 71% | 5.6 |
| June | 76% | 6.2 |
| July | 81% | 6.3 |
| August | 80% | 5.5 |
| September | 79% | 4.4 |
| October | 71% | 3.0 |
| November | 70% | 2.0 |
| December | 66% | 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 Allison need?
A normal year in Allison brings 7,358 heating degree days, 37% more than the median U.S. place (5,373), and 711 cooling degree days, 22% 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 2,854 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,511 | 0 |
| February | 1,247 | 0 |
| March | 969 | 0 |
| April | 537 | 3 |
| May | 217 | 43 |
| June | 28 | 164 |
| July | 5 | 246 |
| August | 16 | 181 |
| September | 135 | 67 |
| October | 473 | 8 |
| November | 905 | 0 |
| December | 1,316 | 0 |
| Year (annual) | 7,358 | 711 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00130157. 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 Allison been warmer than normal lately?
2024 averaged 50.0°F, 3.3°F above the 1991-2020 normal of 46.7°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 48.3°F | +1.6°F | 27.53 |
| 2022 | 45.0°F | −1.7°F | 30.83 |
| 2023 | 48.9°F | +2.2°F | 23.01 |
| 2024 | 50.0°F | +3.3°F | 40.28 |
Over 79 complete years from 1915 to 2024, the station's annual mean temperature rose at a fitted 1.7°F per century (+0.09°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00130157; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Allison's climate compare?
Allison is warmer than 34 of the other 131 places with their own NOAA record in Iowa, and wetter than 45. Across the 7,247 U.S. stations with normals, its annual mean of 46.7°F is warmer than 26%.
In the Köppen classification computed from these normals, Allison 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 Allison share this climate record?
7 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.
- Parkersburg, IA1,986 people · 12 mi S
- Shell Rock, IA1,265 people · 12 mi E
- Clarksville, IA1,238 people · 7 mi E
- Aplington, IA1,088 people · 13 mi S
- Greene, IA971 people · 10 mi N
- Dumont, IA614 people · 9 mi W
- Bristow, IA139 people · 6 mi W
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 Allison's climate
What is the coldest month in Allison?
January, with a normal high of 25°F and a normal low of 8°F. The warmest is July (83°F by day, 63°F at night).
Does it snow in Allison?
Yes. NOAA publishes no 1991-2020 snowfall normal for Allison's NOAA station; the nearest record that keeps one, Charles City (22 miles away), records 38 inches of snow in a normal year.
What is the rainiest month in Allison?
June, with 5.46 in of precipitation in a normal year; the driest is January with 0.94 in.
What plant hardiness zone is Allison in?
The USDA's 2023 map puts Allison in zone 5a in ZIP code 50602, the nearest ZIP area. By the same method at Allison's NOAA station, the coldest night of a typical year reaches −17°F (30 years, 1991-2020): zone 5a.
How late can frost come in Allison?
In half of years the last 32°F night comes after April 27; in one year in ten it comes after May 8. Waiting until May 8 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Hampton, IA21 miles from this station, 46.6°F a year
- Charles City, IA22 miles from this station, 46.5°F a year
- Waterloo, IA25 miles from this station, 49.0°F a year
- Grundy Center, IA27 miles from this station, 47.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made