Grundy Center, Iowa climate: Normal weather by month, frost dates and records
Grundy Center's normal year runs from 9°F January nights to 83°F July afternoons, with 36.8 inches of precipitation and 32 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.4°C, January lows of −13°C, July highs of 28°C, 935 mm of precipitation a year.
- NOAA stationGrundy Center
- Station IDUSC00133487
- Location42.36°N 92.76°W
- Elevation985 ft (300 m)
- From the centerunder 1 mile
- Population2,821
On October 14, the normal high in Grundy Center is 63°F and the normal low 39°F, and the chance of measurable rain or snow is 25%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Grundy Center.
- Jan 26° 9°
- Feb 31° 13°
- Mar 44° 24°
- Apr 59° 36°
- May 70° 48°
- Jun 80° 60°
- Jul 83° 62°
- Aug 81° 60°
- Sep 75° 51°
- Oct 62° 38°
- Nov 45° 26°
- Dec 32° 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 Grundy Center each month?
July is the warmest month, with normal highs of 83°F; January the coldest, with normal lows of 9°F. The most precipitation falls in June (5.65 in), the least in January (0.83 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 26°F | 9°F | 17.4°F | 0.83 | 9.2 | 6 | <1 | 31 | 9 h 20 min |
| February | 31°F | 13°F | 21.7°F | 0.98 | 5.9 | 6 | <1 | 27 | 10 h 30 min |
| March | 44°F | 24°F | 34.2°F | 1.88 | 3.9 | 7 | <1 | 24 | 11 h 50 min |
| April | 59°F | 36°F | 47.1°F | 3.88 | 1.4 | 10 | <1 | 11 | 13 h 20 min |
| May | 70°F | 48°F | 59.3°F | 4.89 | 0.0 | 12 | 1 | 1 | 14 h 30 min |
| June | 80°F | 60°F | 69.7°F | 5.65 | 0.0 | 11 | 3 | <1 | 15 h 20 min |
| July | 83°F | 62°F | 72.7°F | 4.43 | 0.0 | 9 | 4 | <1 | 15 h |
| August | 81°F | 60°F | 70.2°F | 4.80 | 0.0 | 9 | 3 | <1 | 14 h |
| September | 75°F | 51°F | 62.8°F | 3.28 | 0.0 | 8 | 1 | <1 | 12 h 30 min |
| October | 62°F | 38°F | 50.2°F | 2.88 | 0.3 | 8 | <1 | 9 | 11 h 10 min |
| November | 45°F | 26°F | 35.8°F | 1.88 | 2.1 | 7 | <1 | 22 | 9 h 50 min |
| December | 32°F | 15°F | 23.6°F | 1.44 | 9.5 | 7 | <1 | 30 | 9 h 10 min |
| Year (annual) | 57°F | 37°F | 47.1°F | 36.82 | 32.3 | 98 | 11 | 155 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −3°C | −13°C | −8.1°C | 21 mm | 23 cm |
| February | −1°C | −11°C | −5.7°C | 25 mm | 15 cm |
| March | 7°C | −4°C | 1.2°C | 48 mm | 10 cm |
| April | 15°C | 2°C | 8.4°C | 99 mm | 4 cm |
| May | 21°C | 9°C | 15.2°C | 124 mm | 0 cm |
| June | 27°C | 15°C | 20.9°C | 144 mm | 0 cm |
| July | 28°C | 17°C | 22.6°C | 113 mm | 0 cm |
| August | 27°C | 15°C | 21.2°C | 122 mm | 0 cm |
| September | 24°C | 10°C | 17.1°C | 83 mm | 0 cm |
| October | 17°C | 4°C | 10.1°C | 73 mm | 1 cm |
| November | 7°C | −3°C | 2.1°C | 48 mm | 5 cm |
| December | 0°C | −9°C | −4.7°C | 37 mm | 24 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00133487; 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 Grundy Center?
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 (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 USC00133487.
When is the last frost in Grundy Center?
In Grundy Center, the last spring frost (32°F) comes after April 29 in half of years and after May 12 in one year in ten; the first autumn frost comes before October 9 in half of years and before September 25 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 291 year in 10 after May 12; 9 in 10 after April 15
- First autumn frost, half of years before
- October 91 year in 10 before September 25; 9 in 10 before October 20
NOAA puts the median frost-free season at 160 days, and the season without a hard freeze (28°F) at 180 days.
A hard freeze (28°F) comes after April 19 in half of springs and before October 18 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Grundy Center in zone 5a in ZIP code 50638, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Grundy Center's NOAA station is in zone 5a: the coldest night of a typical year reaches −18°F (28 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 USC00133487; 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 Grundy Center?
In a normal year in Grundy Center, 11 days a year reach 90°F, 155 nights fall to 32°F or colder and 98 days bring measurable precipitation.
- Days at 90°F or more
- 11a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 155a normal year
- Days that stay below freezing
- 63high of 32°F or less
- Days with 0.01 inch of precipitation
- 98a normal year
- Days with 1 inch of snow or more
- 11a normal year
The highest temperature in this station's record (since 1893) is 108°F, on August 18, 1936; the lowest is −34°F, on February 13, 1905.
The wettest calendar year on that record is 2018, with 49.14 in; the snowiest season is 1972–73, with 60.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00133487; records: ACIS (NOAA Regional Climate Centers), station USC00133487. Records use complete months only; a month missing more than three days is left out.
How sunny is Grundy Center?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Grundy Center, 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 Grundy Center need?
A normal year in Grundy Center brings 7,227 heating degree days, 35% more than the median U.S. place (5,373), and 730 cooling degree days, 20% 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 2,866 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,476 | 0 |
| February | 1,212 | 0 |
| March | 956 | 1 |
| April | 541 | 4 |
| May | 221 | 46 |
| June | 29 | 172 |
| July | 7 | 245 |
| August | 18 | 181 |
| September | 137 | 73 |
| October | 470 | 9 |
| November | 876 | 0 |
| December | 1,283 | 0 |
| Year (annual) | 7,227 | 730 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00133487. 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 Grundy Center been warmer than normal lately?
2023 averaged 49.5°F, 2.4°F above the 1991-2020 normal of 47.1°F. 2 of the 2 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 48.8°F | +1.6°F | 31.03 | 38.1 |
| 2023 | 49.5°F | +2.4°F | 21.05 | – |
Over 92 complete years from 1895 to 2024, the station's annual mean temperature rose at a fitted 0.4°F per century (+0.02°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00133487; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Grundy Center's climate compare?
Grundy Center is warmer than 49 of the other 131 places with their own NOAA record in Iowa, and wetter than 68. Across the 7,247 U.S. stations with normals, its annual mean of 47.1°F is warmer than 28%.
In the Köppen classification computed from these normals, Grundy Center 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 Grundy Center 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.
- Reinbeck, IA1,673 people · 9 mi E
- Dike, IA1,293 people · 10 mi NE
- Wellsburg, IA709 people · 10 mi NW
- Holland, IA261 people · 3 mi NW
- Stout, IA194 people · 11 mi N
- Lincoln, IA119 people · 8 mi SE
- Morrison, IA101 people · 5 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.
Questions about Grundy Center's climate
What is the coldest month in Grundy Center?
January, with a normal high of 26°F and a normal low of 9°F. The warmest is July (83°F by day, 62°F at night).
Does it snow in Grundy Center?
Yes: 32 inches in a normal year, falling on 19 days with 0.1 inch or more, the most in December (9.5 inches).
What is the rainiest month in Grundy Center?
June, with 5.65 in of precipitation in a normal year; the driest is January with 0.83 in.
What plant hardiness zone is Grundy Center in?
The USDA's 2023 map puts Grundy Center in zone 5a in ZIP code 50638, the nearest ZIP area. By the same method at Grundy Center's NOAA station, the coldest night of a typical year reaches −18°F (28 years, 1991-2020): zone 5a.
How late can frost come in Grundy Center?
In half of years the last 32°F night comes after April 29; in one year in ten it comes after May 12. Waiting until May 12 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Eldora, IA17 miles from this station, 46.9°F a year
- Marshalltown, IA19 miles from this station, 47.7°F a year
- Waterloo, IA22 miles from this station, 49.0°F a year
- Toledo, IA24 miles from this station, 47.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made