Northwood, Iowa climate: Normal weather by month, frost dates and records
Northwood's normal year runs from 4°F January nights to 79°F July afternoons, with 35.5 inches of precipitation and 40 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.1°C, January lows of −16°C, July highs of 26°C, 901 mm of precipitation a year.
- NOAA stationNorthwood
- Station IDUSC00136103
- Location43.44°N 93.23°W
- Elevation1,190 ft (363 m)
- Population2,047
On October 23, the normal high in Northwood is 53°F and the normal low 32°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 Northwood.
- Jan 21° 4°
- Feb 26° 8°
- Mar 38° 21°
- Apr 54° 33°
- May 66° 45°
- Jun 76° 56°
- Jul 79° 59°
- Aug 76° 57°
- Sep 71° 48°
- Oct 57° 35°
- Nov 41° 23°
- Dec 27° 11°
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 Northwood each month?
July is the warmest month, with normal highs of 79°F; January the coldest, with normal lows of 4°F. The most precipitation falls in June (5.13 in), the least in February (1.02 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 21°F | 4°F | 12.6°F | 1.07 | 10.9 | 8 | <1 | 31 | 9 h 20 min |
| February | 26°F | 8°F | 16.9°F | 1.02 | 9.3 | 6 | <1 | 27 | 10 h 30 min |
| March | 38°F | 21°F | 29.5°F | 1.99 | 6.2 | 8 | <1 | 26 | 11 h 50 min |
| April | 54°F | 33°F | 43.3°F | 3.82 | 3.3 | 10 | <1 | 12 | 13 h 20 min |
| May | 66°F | 45°F | 55.6°F | 4.78 | 0.0 | 12 | 1 | 1 | 14 h 40 min |
| June | 76°F | 56°F | 65.9°F | 5.13 | 0.0 | 11 | 1 | <1 | 15 h 20 min |
| July | 79°F | 59°F | 69.0°F | 4.73 | 0.0 | 9 | 2 | <1 | 15 h 10 min |
| August | 76°F | 57°F | 66.5°F | 3.92 | 0.0 | 8 | 1 | <1 | 14 h |
| September | 71°F | 48°F | 59.3°F | 3.32 | 0.0 | 8 | <1 | 1 | 12 h 30 min |
| October | 57°F | 35°F | 46.1°F | 2.68 | 0.3 | 8 | <1 | 11 | 11 h 10 min |
| November | 41°F | 23°F | 31.7°F | 1.73 | 2.6 | 7 | <1 | 24 | 9 h 40 min |
| December | 27°F | 11°F | 19.4°F | 1.28 | 7.6 | 7 | <1 | 30 | 9 h |
| Year (annual) | 53°F | 33°F | 43.0°F | 35.47 | 40.2 | 101 | 4 | 165 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −6°C | −16°C | −10.8°C | 27 mm | 28 cm |
| February | −4°C | −13°C | −8.4°C | 26 mm | 24 cm |
| March | 4°C | −6°C | −1.4°C | 51 mm | 16 cm |
| April | 12°C | 0°C | 6.3°C | 97 mm | 8 cm |
| May | 19°C | 7°C | 13.1°C | 121 mm | 0 cm |
| June | 24°C | 13°C | 18.8°C | 130 mm | 0 cm |
| July | 26°C | 15°C | 20.6°C | 120 mm | 0 cm |
| August | 25°C | 14°C | 19.2°C | 100 mm | 0 cm |
| September | 22°C | 9°C | 15.2°C | 84 mm | 0 cm |
| October | 14°C | 2°C | 7.8°C | 68 mm | 1 cm |
| November | 5°C | −5°C | −0.2°C | 44 mm | 7 cm |
| December | −3°C | −11°C | −7.0°C | 33 mm | 19 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00136103; 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 Northwood?
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 USC00136103.
When is the last frost in Northwood?
In Northwood, the last spring frost (32°F) comes after May 4 in half of years and after May 16 in one year in ten; the first autumn frost comes before October 4 in half of years and before September 20 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 41 year in 10 after May 16; 9 in 10 after April 21
- First autumn frost, half of years before
- October 41 year in 10 before September 20; 9 in 10 before October 17
NOAA puts the median frost-free season at 152 days, and the season without a hard freeze (28°F) at 172 days.
A hard freeze (28°F) comes after April 24 in half of springs and before October 13 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Northwood in zone 5a in ZIP code 50459, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Northwood's NOAA station is in zone 4b: the coldest night of a typical year reaches −20°F (17 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 USC00136103; 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 Northwood?
In a normal year in Northwood, 4 days a year reach 90°F, 165 nights fall to 32°F or colder and 101 days bring measurable precipitation.
- Days at 90°F or more
- 4a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 165a normal year
- Days that stay below freezing
- 79high of 32°F or less
- Days with 0.01 inch of precipitation
- 101a normal year
- Days with 1 inch of snow or more
- 12a normal year
The highest temperature in this station's record (since 1896) is 107°F, on July 14, 1936; the lowest is −37°F, on January 12, 1912.
The wettest calendar year on that record is 1990, with 50.03 in; the snowiest season is 1950–51, with 73.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00136103; records: ACIS (NOAA Regional Climate Centers), station USC00136103. Records use complete months only; a month missing more than three days is left out.
How sunny is Northwood?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Northwood, 4.0 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (65%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 70% | 1.9 |
| February | 76% | 3.0 |
| March | 71% | 3.8 |
| April | 69% | 4.8 |
| May | 70% | 5.5 |
| June | 75% | 6.2 |
| July | 82% | 6.5 |
| August | 80% | 5.5 |
| September | 78% | 4.3 |
| October | 70% | 2.9 |
| November | 69% | 1.9 |
| December | 65% | 1.4 |
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 Northwood need?
A normal year in Northwood brings 8,378 heating degree days, 56% more than the median U.S. place (5,373), and 392 cooling degree days, 57% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,225 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,626 | 0 |
| February | 1,348 | 0 |
| March | 1,101 | 0 |
| April | 652 | 1 |
| May | 312 | 21 |
| June | 67 | 95 |
| July | 22 | 146 |
| August | 47 | 93 |
| September | 203 | 33 |
| October | 589 | 3 |
| November | 999 | 0 |
| December | 1,414 | 0 |
| Year (annual) | 8,378 | 392 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00136103. 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 Northwood been warmer than normal lately?
Over 71 complete years from 1897 to 2024, the station's annual mean temperature rose at a fitted 0.2°F per century (+0.01°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Northwood's climate compare?
Northwood is warmer than 0 of the other 131 places with their own NOAA record in Iowa, and wetter than 46. Across the 7,247 U.S. stations with normals, its annual mean of 43.0°F is warmer than 12%.
In the Köppen classification computed from these normals, Northwood is Dfb: continental, no dry season, warm 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 Northwood share this climate record?
10 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.
- Manly, IA1,233 people · 10 mi S
- Glenville, MN558 people · 10 mi N
- Lyle, MN526 people · 15 mi E
- Emmons, MN360 people · 14 mi W
- Kensett, IA256 people · 6 mi S
- Grafton, IA212 people · 11 mi SE
- Conger, MN151 people · 19 mi NW
- Twin Lakes, MN130 people · 13 mi NW
- Myrtle, MN49 people · 9 mi N
- Bolan, IA0 people · 7 mi SE
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 Northwood's climate
What is the coldest month in Northwood?
January, with a normal high of 21°F and a normal low of 4°F. The warmest is July (79°F by day, 59°F at night).
Does it snow in Northwood?
Yes: 40 inches in a normal year, falling on 23 days with 0.1 inch or more, the most in January (10.9 inches).
What is the rainiest month in Northwood?
June, with 5.13 in of precipitation in a normal year; the driest is February with 1.02 in.
What plant hardiness zone is Northwood in?
The USDA's 2023 map puts Northwood in zone 5a in ZIP code 50459, the nearest ZIP area. By the same method at Northwood's NOAA station, the coldest night of a typical year reaches −20°F (17 years, 1991-2020): zone 4b.
How late can frost come in Northwood?
In half of years the last 32°F night comes after May 4; in one year in ten it comes after May 16. Waiting until May 16 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Albert Lea, MN12 miles from this station, 45.2°F a year
- Austin, MN19 miles from this station, 44.6°F a year
- Mason City, IA21 miles from this station, 45.6°F a year
- Forest City, IA23 miles from this station, 44.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made