Ames, Iowa climate: Normal weather by month, frost dates and records
Ames's normal year runs from 11°F January nights to 84°F July afternoons, with 35.9 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.2°C, January lows of −12°C, July highs of 29°C, 912 mm of precipitation a year.
- NOAA stationAmes Municipal Airport
- Station IDUSW00094989
- Location41.99°N 93.62°W
- Elevation930 ft (284 m)
- From the center2 miles
- Population69,026
On October 22, the normal high in Ames is 59°F and the normal low 37°F, and the chance of measurable rain or snow is 28%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Ames.
- Jan 29° 11°
- Feb 33° 15°
- Mar 47° 27°
- Apr 61° 38°
- May 72° 50°
- Jun 81° 60°
- Jul 84° 63°
- Aug 82° 60°
- Sep 76° 51°
- Oct 63° 39°
- Nov 47° 27°
- Dec 34° 17°
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 Ames each month?
July is the warmest month, with normal highs of 84°F; January the coldest, with normal lows of 11°F. The most precipitation falls in June (5.22 in), the least in January (0.61 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 29°F | 11°F | 19.8°F | 0.61 | 6 | <1 | 30 | 9 h 30 min |
| February | 33°F | 15°F | 24.4°F | 0.78 | 6 | <1 | 27 | 10 h 30 min |
| March | 47°F | 27°F | 37.0°F | 1.95 | 8 | <1 | 23 | 11 h 50 min |
| April | 61°F | 38°F | 49.4°F | 3.89 | 12 | <1 | 8 | 13 h 20 min |
| May | 72°F | 50°F | 60.7°F | 5.16 | 14 | 1 | 1 | 14 h 30 min |
| June | 81°F | 60°F | 70.6°F | 5.22 | 13 | 4 | <1 | 15 h 10 min |
| July | 84°F | 63°F | 73.3°F | 4.44 | 11 | 7 | <1 | 15 h |
| August | 82°F | 60°F | 71.0°F | 4.85 | 12 | 3 | <1 | 14 h |
| September | 76°F | 51°F | 63.4°F | 3.31 | 10 | 2 | <1 | 12 h 30 min |
| October | 63°F | 39°F | 50.9°F | 2.77 | 9 | <1 | 8 | 11 h 10 min |
| November | 47°F | 27°F | 36.9°F | 1.88 | 6 | <1 | 21 | 9 h 50 min |
| December | 34°F | 17°F | 25.2°F | 1.05 | 6 | <1 | 29 | 9 h 10 min |
| Year (annual) | 59°F | 38°F | 48.5°F | 35.91 | 112 | 17 | 147 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −2°C | −12°C | −6.8°C | 15 mm |
| February | 1°C | −9°C | −4.2°C | 20 mm |
| March | 8°C | −3°C | 2.8°C | 50 mm |
| April | 16°C | 3°C | 9.7°C | 99 mm |
| May | 22°C | 10°C | 15.9°C | 131 mm |
| June | 27°C | 15°C | 21.4°C | 133 mm |
| July | 29°C | 17°C | 22.9°C | 113 mm |
| August | 28°C | 16°C | 21.7°C | 123 mm |
| September | 24°C | 11°C | 17.4°C | 84 mm |
| October | 17°C | 4°C | 10.5°C | 70 mm |
| November | 8°C | −3°C | 2.7°C | 48 mm |
| December | 1°C | −9°C | −3.8°C | 27 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Ames's own co-op station Ames (5 mi SE) does: 27 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094989; 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 Ames?
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 (10).
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 USW00094989.
When is the last frost in Ames?
In Ames, the last spring frost (32°F) comes after April 26 in half of years and after May 9 in one year in ten; the first autumn frost comes before October 8 in half of years and before September 23 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 261 year in 10 after May 9; 9 in 10 after April 11
- First autumn frost, half of years before
- October 81 year in 10 before September 23; 9 in 10 before October 21
NOAA puts the median frost-free season at 164 days, and the season without a hard freeze (28°F) at 184 days.
A hard freeze (28°F) comes after April 14 in half of springs and before October 19 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Ames in zone 5b across its 4 ZIP code areas (5b in 50010, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Ames's NOAA station is in zone 5a: the coldest night of a typical year reaches −17°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 USW00094989; 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.
What hardiness zone is each Ames ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Ames's 4 ZIP code areas are all in zone 5b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Ames?
In a normal year in Ames, 17 days a year reach 90°F, 147 nights fall to 32°F or colder and 112 days bring measurable precipitation.
- Days at 90°F or more
- 17a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 147a normal year
- Days that stay below freezing
- 53high of 32°F or less
- Days with 0.01 inch of precipitation
- 112a normal year
The highest temperature in this station's record (since 1996) is 101°F, on June 17, 2021; the lowest is −31°F, on January 16, 2009.
The wettest calendar year on that record is 2010, with 52.52 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00094989; records: ACIS (NOAA Regional Climate Centers), station USW00094989. Records use complete months only; a month missing more than three days is left out.
How sunny is Ames?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Ames, 4.1 kWh per square metre a day. July is the sunniest month (81%) and December the cloudiest (68%). Among the 459 U.S. places of 50,000 or more, that ranks tied 304th (with 25 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 68% | 2.0 |
| February | 74% | 3.0 |
| March | 70% | 3.8 |
| April | 69% | 4.8 |
| May | 72% | 5.7 |
| June | 77% | 6.3 |
| July | 81% | 6.4 |
| August | 80% | 5.5 |
| September | 80% | 4.6 |
| October | 73% | 3.1 |
| November | 72% | 2.2 |
| December | 68% | 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 Ames need?
A normal year in Ames brings 6,749 heating degree days, 26% more than the median U.S. place (5,373), and 786 cooling degree days, 13% 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 3,021 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,401 | 0 |
| February | 1,137 | 0 |
| March | 867 | 1 |
| April | 474 | 4 |
| May | 186 | 51 |
| June | 21 | 187 |
| July | 4 | 263 |
| August | 12 | 196 |
| September | 122 | 74 |
| October | 448 | 10 |
| November | 843 | 0 |
| December | 1,234 | 0 |
| Year (annual) | 6,749 | 786 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094989. 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 Ames been warmer than normal lately?
2025 averaged 50.4°F, 1.9°F above the 1991-2020 normal of 48.5°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 50.6°F | +2.1°F | – |
| 2022 | 48.3°F | −0.2°F | – |
| 2023 | 51.6°F | +3.1°F | 30.78 |
| 2024 | 52.6°F | +4.1°F | – |
| 2025 | 50.4°F | +1.9°F | – |
Source: observed years: ACIS, station USW00094989. A year counts only with all twelve months complete.
How does Ames's climate compare?
Ames is warmer than 76 of the other 131 places with their own NOAA record in Iowa, and wetter than 49. Across the 7,247 U.S. stations with normals, its annual mean of 48.5°F is warmer than 34%.
In the Köppen classification computed from these normals, Ames 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 Ames 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.
- Huxley, IA4,737 people · 7 mi S
- Story City, IA3,439 people · 13 mi N
- Slater, IA1,626 people · 9 mi SW
- Gilbert, IA1,397 people · 8 mi N
- Roland, IA1,376 people · 13 mi NE
- Cambridge, IA844 people · 8 mi SE
- Kelley, IA312 people · 4 mi SW
- Randall, IA156 people · 17 mi N
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 Ames's other NOAA stations record?
2 more NOAA stations keep 1991-2020 normals in or near Ames. This page uses Ames Municipal Airport; the others differ by site and elevation:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Ames (5 mi SE) USC00130203 | 6 mi SE | 870 ft | 48.0°F | 10°F | 84°F | 38.1 | 27 | April 26 |
| Ames (8 mi WSW) USC00130200 | 8 mi W | 1,099 ft | 49.4°F | 12°F | 84°F | 35.9 | 33 | April 23 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Ames's climate
What is the coldest month in Ames?
January, with a normal high of 29°F and a normal low of 11°F. The warmest is July (84°F by day, 63°F at night).
Does it snow in Ames?
Yes. NOAA publishes no 1991-2020 snowfall normal for Ames's NOAA station; Ames's own co-op station Ames (5 mi SE) records 27 inches of snow in a normal year.
What is the rainiest month in Ames?
June, with 5.22 in of precipitation in a normal year; the driest is January with 0.61 in.
What plant hardiness zone is Ames in?
The USDA's 2023 map puts Ames in zone 5b across its 4 ZIP code areas (5b in 50010, the largest). By the same method at Ames's NOAA station, the coldest night of a typical year reaches −17°F (24 years, 1991-2020): zone 5a.
How late can frost come in Ames?
In half of years the last 32°F night comes after April 26; 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
- Ames in OctoberThis month day by day, its records and recent years
- Iowa climateThe statewide normals and every place in the state
- Boone, IA14 miles from this station, 48.1°F a year
- Colo, IA16 miles from this station, 47.8°F a year
- Ankeny, IA18 miles from this station, 49.5°F a year
- Des Moines Weather Office-Johnston, IA19 miles from this station, 50.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made