Mount Ayr, Iowa climate: Normal weather by month, frost dates and records
Mount Ayr's normal year runs from 12°F January nights to 85°F July afternoons, with 37.0 inches of precipitation and 21 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.8°C, January lows of −11°C, July highs of 29°C, 939 mm of precipitation a year.
- NOAA stationMount Ayr
- Station IDUSC00135769
- Location40.71°N 94.24°W
- Elevation1,140 ft (348 m)
- Population1,616
On October 14, the normal high in Mount Ayr is 65°F and the normal low 41°F, and the chance of measurable rain or snow is 22%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Mount Ayr.
- Jan 32° 12°
- Feb 37° 16°
- Mar 49° 28°
- Apr 61° 38°
- May 71° 50°
- Jun 80° 60°
- Jul 85° 64°
- Aug 83° 62°
- Sep 76° 53°
- Oct 64° 40°
- Nov 49° 28°
- Dec 37° 18°
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 Mount Ayr each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 12°F. The most precipitation falls in June (5.39 in), the least in January (0.73 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 32°F | 12°F | 21.8°F | 0.73 | 5.8 | 4 | <1 | 30 | 9 h 30 min |
| February | 37°F | 16°F | 26.5°F | 1.25 | 5.9 | 5 | <1 | 26 | 10 h 40 min |
| March | 49°F | 28°F | 38.5°F | 2.16 | 2.6 | 6 | <1 | 22 | 11 h 50 min |
| April | 61°F | 38°F | 49.7°F | 3.37 | 0.7 | 9 | <1 | 9 | 13 h 20 min |
| May | 71°F | 50°F | 60.2°F | 5.35 | 0.0 | 11 | <1 | 1 | 14 h 20 min |
| June | 80°F | 60°F | 70.0°F | 5.39 | 0.0 | 9 | 2 | <1 | 15 h |
| July | 85°F | 64°F | 74.2°F | 4.40 | 0.0 | 8 | 7 | <1 | 14 h 50 min |
| August | 83°F | 62°F | 72.5°F | 3.98 | 0.0 | 8 | 5 | <1 | 13 h 50 min |
| September | 76°F | 53°F | 64.5°F | 3.71 | 0.0 | 7 | 2 | <1 | 12 h 30 min |
| October | 64°F | 40°F | 52.1°F | 2.88 | 0.3 | 7 | <1 | 7 | 11 h 10 min |
| November | 49°F | 28°F | 38.4°F | 2.11 | 1.2 | 5 | <1 | 20 | 10 h |
| December | 37°F | 18°F | 27.2°F | 1.63 | 4.0 | 5 | <1 | 29 | 9 h 20 min |
| Year (annual) | 60°F | 39°F | 49.6°F | 36.96 | 20.5 | 83 | 16 | 143 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 0°C | −11°C | −5.7°C | 19 mm | 15 cm |
| February | 3°C | −9°C | −3.1°C | 32 mm | 15 cm |
| March | 10°C | −2°C | 3.6°C | 55 mm | 7 cm |
| April | 16°C | 3°C | 9.8°C | 86 mm | 2 cm |
| May | 22°C | 10°C | 15.7°C | 136 mm | 0 cm |
| June | 27°C | 15°C | 21.1°C | 137 mm | 0 cm |
| July | 29°C | 18°C | 23.4°C | 112 mm | 0 cm |
| August | 29°C | 17°C | 22.5°C | 101 mm | 0 cm |
| September | 25°C | 12°C | 18.1°C | 94 mm | 0 cm |
| October | 18°C | 5°C | 11.2°C | 73 mm | 1 cm |
| November | 9°C | −2°C | 3.6°C | 54 mm | 3 cm |
| December | 3°C | −8°C | −2.7°C | 41 mm | 10 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00135769; 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 Mount Ayr?
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 USC00135769.
When is the last frost in Mount Ayr?
In Mount Ayr, the last spring frost (32°F) comes after April 25 in half of years and after May 9 in one year in ten; the first autumn frost comes before October 12 in half of years and before September 27 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 251 year in 10 after May 9; 9 in 10 after April 10
- First autumn frost, half of years before
- October 121 year in 10 before September 27; 9 in 10 before October 25
NOAA puts the median frost-free season at 169 days, and the season without a hard freeze (28°F) at 191 days.
A hard freeze (28°F) comes after April 14 in half of springs and before October 23 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Mount Ayr in zone 5b in ZIP code 50854, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Mount Ayr's NOAA station is in zone 5a: the coldest night of a typical year reaches −16°F (19 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 USC00135769; 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 Mount Ayr?
In a normal year in Mount Ayr, 16 days a year reach 90°F, 143 nights fall to 32°F or colder and 83 days bring measurable precipitation.
- Days at 90°F or more
- 16a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 143a normal year
- Days that stay below freezing
- 45high of 32°F or less
- Days with 0.01 inch of precipitation
- 83a normal year
- Days with 1 inch of snow or more
- 7a normal year
The highest temperature in this station's record (since 1893) is 112°F, on July 25, 1936; the lowest is −30°F, on January 12, 1912.
The wettest calendar year on that record is 2010, with 61.06 in; the snowiest season is 1935–36, with 41.2 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00135769; records: ACIS (NOAA Regional Climate Centers), station USC00135769. Records use complete months only; a month missing more than three days is left out.
How sunny is Mount Ayr?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Mount Ayr, 4.2 kWh per square metre a day. July is the sunniest month (82%) and March the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 71% | 2.1 |
| February | 73% | 3.0 |
| March | 70% | 3.9 |
| April | 71% | 5.0 |
| May | 73% | 5.8 |
| June | 79% | 6.4 |
| July | 82% | 6.5 |
| August | 81% | 5.7 |
| September | 81% | 4.7 |
| October | 75% | 3.3 |
| November | 74% | 2.3 |
| December | 70% | 1.8 |
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 Mount Ayr need?
A normal year in Mount Ayr brings 6,422 heating degree days, 20% more than the median U.S. place (5,373), and 865 cooling degree days, 5% 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 3,158 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,339 | 0 |
| February | 1,079 | 0 |
| March | 824 | 1 |
| April | 464 | 5 |
| May | 193 | 46 |
| June | 26 | 175 |
| July | 4 | 291 |
| August | 9 | 243 |
| September | 107 | 94 |
| October | 410 | 12 |
| November | 797 | 0 |
| December | 1,170 | 0 |
| Year (annual) | 6,422 | 865 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00135769. 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 Mount Ayr been warmer than normal lately?
2022 averaged 48.9°F, 0.7°F below the 1991-2020 normal of 49.6°F. 1 of the 2 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 51.3°F | +1.7°F | 36.68 | 22.3 |
| 2022 | 48.9°F | −0.7°F | 28.23 | 27.3 |
Over 71 complete years from 1896 to 2022, the station's annual mean temperature rose at a fitted -0.0°F per century (−0.00°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00135769; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Mount Ayr's climate compare?
Mount Ayr is warmer than 99 of the other 131 places with their own NOAA record in Iowa, and wetter than 69. Across the 7,247 U.S. stations with normals, its annual mean of 49.6°F is warmer than 38%.
In the Köppen classification computed from these normals, Mount Ayr 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 Mount Ayr share this climate record?
2 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.
- Diagonal, IA331 people · 9 mi NW
- Allendale, MO46 people · 15 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 Mount Ayr's climate
What is the coldest month in Mount Ayr?
January, with a normal high of 32°F and a normal low of 12°F. The warmest is July (85°F by day, 64°F at night).
Does it snow in Mount Ayr?
Yes: 21 inches in a normal year, falling on 11 days with 0.1 inch or more, the most in February (5.9 inches).
What is the rainiest month in Mount Ayr?
June, with 5.39 in of precipitation in a normal year; the driest is January with 0.73 in.
What plant hardiness zone is Mount Ayr in?
The USDA's 2023 map puts Mount Ayr in zone 5b in ZIP code 50854, the nearest ZIP area. By the same method at Mount Ayr's NOAA station, the coldest night of a typical year reaches −16°F (19 years, 1991-2020): zone 5a.
How late can frost come in Mount Ayr?
In half of years the last 32°F night comes after April 25; in one year in ten it comes after May 9. Waiting until May 9 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Beaconsfield, IA12 miles from this station, 49.2°F a year
- Grant City, MO17 miles from this station, 50.4°F a year
- Lamoni, IA19 miles from this station, 51.6°F a year
- Creston, IA24 miles from this station, 48.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made