Newton, Iowa climate: Normal weather by month, frost dates and records
Newton's normal year runs from 10°F January nights to 85°F July afternoons, with 35.1 inches of precipitation and 29 inches of snow 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, 893 mm of precipitation a year.
- NOAA stationNewton
- Station IDUSC00135992
- Location41.71°N 93.03°W
- Elevation960 ft (293 m)
- From the center1 miles
- Population15,709
On October 23, the normal high in Newton is 59°F and the normal low 38°F, and the chance of measurable rain or snow is 24%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Newton.
- Jan 28° 10°
- Feb 33° 14°
- Mar 46° 26°
- Apr 60° 37°
- May 71° 50°
- Jun 81° 60°
- Jul 85° 64°
- Aug 83° 61°
- Sep 76° 52°
- Oct 63° 40°
- 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 Newton each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 10°F. The most precipitation falls in June (5.01 in), the least in January (0.93 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 28°F | 10°F | 19.2°F | 0.93 | 9.2 | 6 | <1 | 30 | 9 h 30 min |
| February | 33°F | 14°F | 23.7°F | 1.10 | 6.0 | 6 | <1 | 26 | 10 h 30 min |
| March | 46°F | 26°F | 36.1°F | 2.06 | 4.5 | 8 | <1 | 22 | 11 h 50 min |
| April | 60°F | 37°F | 48.8°F | 3.44 | 0.8 | 10 | <1 | 8 | 13 h 20 min |
| May | 71°F | 50°F | 60.6°F | 4.84 | 0.0 | 12 | 1 | <1 | 14 h 30 min |
| June | 81°F | 60°F | 70.6°F | 5.01 | 0.0 | 11 | 5 | <1 | 15 h 10 min |
| July | 85°F | 64°F | 74.2°F | 3.93 | 0.0 | 8 | 8 | <1 | 15 h |
| August | 83°F | 61°F | 72.0°F | 4.30 | 0.0 | 9 | 5 | <1 | 13 h 50 min |
| September | 76°F | 52°F | 64.3°F | 3.59 | 0.0 | 7 | 2 | <1 | 12 h 30 min |
| October | 63°F | 40°F | 51.5°F | 2.66 | 0.3 | 8 | <1 | 6 | 11 h 10 min |
| November | 47°F | 27°F | 37.0°F | 2.01 | 1.6 | 6 | <1 | 21 | 9 h 50 min |
| December | 34°F | 17°F | 25.2°F | 1.27 | 6.3 | 7 | <1 | 29 | 9 h 10 min |
| Year (annual) | 59°F | 38°F | 48.6°F | 35.14 | 28.7 | 98 | 21 | 142 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −12°C | −7.1°C | 24 mm | 23 cm |
| February | 1°C | −10°C | −4.6°C | 28 mm | 15 cm |
| March | 8°C | −3°C | 2.3°C | 52 mm | 11 cm |
| April | 16°C | 3°C | 9.3°C | 87 mm | 2 cm |
| May | 22°C | 10°C | 15.9°C | 123 mm | 0 cm |
| June | 27°C | 16°C | 21.4°C | 127 mm | 0 cm |
| July | 29°C | 18°C | 23.4°C | 100 mm | 0 cm |
| August | 28°C | 16°C | 22.2°C | 109 mm | 0 cm |
| September | 25°C | 11°C | 17.9°C | 91 mm | 0 cm |
| October | 17°C | 5°C | 10.8°C | 68 mm | 1 cm |
| November | 8°C | −3°C | 2.8°C | 51 mm | 4 cm |
| December | 1°C | −8°C | −3.8°C | 32 mm | 16 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00135992; 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 Newton?
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 USC00135992.
When is the last frost in Newton?
In Newton, the last spring frost (32°F) comes after April 22 in half of years and after May 4 in one year in ten; the first autumn frost comes before October 17 in half of years and before October 1 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 221 year in 10 after May 4; 9 in 10 after April 8
- First autumn frost, half of years before
- October 171 year in 10 before October 1; 9 in 10 before October 28
NOAA puts the median frost-free season at 174 days, and the season without a hard freeze (28°F) at 194 days.
A hard freeze (28°F) comes after April 12 in half of springs and before October 26 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Newton in zone 5b in ZIP code 50208, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Newton's NOAA station is in zone 5b: the coldest night of a typical year reaches −13°F (26 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 USC00135992; 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 Newton?
In a normal year in Newton, 21 days a year reach 90°F, 142 nights fall to 32°F or colder and 98 days bring measurable precipitation.
- Days at 90°F or more
- 21a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 142a normal year
- Days that stay below freezing
- 53high 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 107°F, on July 24, 1901; the lowest is −34°F, on February 13, 1905.
The wettest calendar year on that record is 2010, with 56.95 in; the snowiest season is 1961–62, with 55.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00135992; records: ACIS (NOAA Regional Climate Centers), station USC00135992. Records use complete months only; a month missing more than three days is left out.
How sunny is Newton?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Newton, 4.1 kWh per square metre a day. July is the sunniest month (81%) and December the cloudiest (68%).
| 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 Newton need?
A normal year in Newton brings 6,803 heating degree days, 27% more than the median U.S. place (5,373), and 862 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 3,112 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,420 | 0 |
| February | 1,156 | 0 |
| March | 897 | 1 |
| April | 492 | 4 |
| May | 190 | 54 |
| June | 23 | 191 |
| July | 3 | 288 |
| August | 10 | 225 |
| September | 110 | 89 |
| October | 431 | 11 |
| November | 840 | 0 |
| December | 1,232 | 0 |
| Year (annual) | 6,803 | 862 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00135992. 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 Newton been warmer than normal lately?
2023 averaged 51.0°F, 2.4°F above the 1991-2020 normal of 48.6°F. 2 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 50.5°F | +1.9°F | 27.81 | 32.1 |
| 2022 | 47.8°F | −0.8°F | 25.84 | 32.4 |
| 2023 | 51.0°F | +2.4°F | 28.87 | – |
Over 55 complete years from 1949 to 2023, the station's annual mean temperature rose at a fitted 2.7°F per century (+0.15°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00135992; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Newton's climate compare?
Newton is warmer than 81 of the other 131 places with their own NOAA record in Iowa, and wetter than 41. Across the 7,247 U.S. stations with normals, its annual mean of 48.6°F is warmer than 34%.
In the Köppen classification computed from these normals, Newton 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 Newton share this climate record?
9 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.
- Colfax, IA2,305 people · 11 mi W
- Prairie City, IA1,722 people · 13 mi SW
- Baxter, IA983 people · 10 mi NW
- Kellogg, IA597 people · 6 mi E
- Mingo, IA314 people · 14 mi W
- Laurel, IA214 people · 13 mi NE
- Lambs Grove, IA174 people · 3 mi W
- Reasnor, IA157 people · 9 mi S
- Valeria, IA41 people · 15 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 Newton's climate
What is the coldest month in Newton?
January, with a normal high of 28°F and a normal low of 10°F. The warmest is July (85°F by day, 64°F at night).
Does it snow in Newton?
Yes: 29 inches in a normal year, falling on 15 days with 0.1 inch or more, the most in January (9.2 inches).
What is the rainiest month in Newton?
June, with 5.01 in of precipitation in a normal year; the driest is January with 0.93 in.
What plant hardiness zone is Newton in?
The USDA's 2023 map puts Newton in zone 5b in ZIP code 50208, the nearest ZIP area. By the same method at Newton's NOAA station, the coldest night of a typical year reaches −13°F (26 years, 1991-2020): zone 5b.
How late can frost come in Newton?
In half of years the last 32°F night comes after April 22; in one year in ten it comes after May 4. Waiting until May 4 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Grinnell, IA14 miles from this station, 47.5°F a year
- Colo, IA26 miles from this station, 47.8°F a year
- Knoxville, IA27 miles from this station, 49.9°F a year
- Marshalltown, IA29 miles from this station, 47.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made