Castana, Iowa climate: Normal weather by month, frost dates and records
Castana's normal year runs from 10°F January nights to 84°F July afternoons, with 32.1 inches of precipitation and 29 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.0°C, January lows of −12°C, July highs of 29°C, 816 mm of precipitation a year.
- NOAA stationCastana Experiment Farm
- Station IDUSC00131277
- Location42.06°N 95.84°W
- Elevation1,400 ft (427 m)
- Population103
On October 14, the normal high in Castana is 64°F and the normal low 41°F, and the chance of measurable rain or snow is 23%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Castana.
- Jan 29° 10°
- Feb 33° 14°
- Mar 47° 26°
- Apr 60° 37°
- May 71° 49°
- Jun 80° 60°
- Jul 84° 64°
- Aug 82° 61°
- Sep 75° 53°
- Oct 63° 40°
- Nov 47° 26°
- Dec 33° 16°
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 Castana each month?
July is the warmest month, with normal highs of 84°F; January the coldest, with normal lows of 10°F. The most precipitation falls in June (4.84 in), the least in January (0.63 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 29°F | 10°F | 19.5°F | 0.63 | 7.1 | 5 | <1 | 30 | 9 h 30 min |
| February | 33°F | 14°F | 23.9°F | 0.71 | 7.2 | 5 | <1 | 26 | 10 h 30 min |
| March | 47°F | 26°F | 36.1°F | 1.69 | 4.2 | 7 | <1 | 23 | 11 h 50 min |
| April | 60°F | 37°F | 48.2°F | 3.32 | 1.7 | 10 | <1 | 8 | 13 h 20 min |
| May | 71°F | 49°F | 60.0°F | 4.66 | 0.0 | 13 | <1 | 1 | 14 h 30 min |
| June | 80°F | 60°F | 70.0°F | 4.84 | 0.0 | 11 | 2 | <1 | 15 h 10 min |
| July | 84°F | 64°F | 73.7°F | 4.02 | 0.0 | 10 | 6 | <1 | 15 h |
| August | 82°F | 61°F | 71.3°F | 4.23 | 0.0 | 9 | 3 | <1 | 14 h |
| September | 75°F | 53°F | 63.9°F | 3.05 | 0.0 | 8 | 2 | <1 | 12 h 30 min |
| October | 63°F | 40°F | 51.2°F | 2.43 | 0.7 | 7 | <1 | 7 | 11 h 10 min |
| November | 47°F | 26°F | 36.4°F | 1.50 | 2.0 | 5 | <1 | 21 | 9 h 50 min |
| December | 33°F | 16°F | 24.5°F | 1.03 | 5.7 | 6 | <1 | 30 | 9 h 10 min |
| Year (annual) | 59°F | 38°F | 48.2°F | 32.11 | 28.6 | 96 | 13 | 144 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −12°C | −6.9°C | 16 mm | 18 cm |
| February | 1°C | −10°C | −4.5°C | 18 mm | 18 cm |
| March | 8°C | −4°C | 2.3°C | 43 mm | 11 cm |
| April | 15°C | 3°C | 9.0°C | 84 mm | 4 cm |
| May | 21°C | 10°C | 15.6°C | 118 mm | 0 cm |
| June | 27°C | 15°C | 21.1°C | 123 mm | 0 cm |
| July | 29°C | 18°C | 23.2°C | 102 mm | 0 cm |
| August | 28°C | 16°C | 21.8°C | 107 mm | 0 cm |
| September | 24°C | 11°C | 17.7°C | 77 mm | 0 cm |
| October | 17°C | 4°C | 10.7°C | 62 mm | 2 cm |
| November | 8°C | −3°C | 2.4°C | 38 mm | 5 cm |
| December | 1°C | −9°C | −4.2°C | 26 mm | 14 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00131277; 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 Castana?
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 USC00131277.
When is the last frost in Castana?
In Castana, the last spring frost (32°F) comes after April 25 in half of years and after May 7 in one year in ten; the first autumn frost comes before October 12 in half of years and before September 28 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 7; 9 in 10 after April 11
- First autumn frost, half of years before
- October 121 year in 10 before September 28; 9 in 10 before October 27
NOAA puts the median frost-free season at 170 days, and the season without a hard freeze (28°F) at 189 days.
A hard freeze (28°F) comes after April 15 in half of springs and before October 23 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Castana in zone 5b in ZIP code 51010, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Castana's NOAA station is in zone 5b: the coldest night of a typical year reaches −14°F (27 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 USC00131277; 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 Castana?
In a normal year in Castana, 13 days a year reach 90°F, 144 nights fall to 32°F or colder and 96 days bring measurable precipitation.
- Days at 90°F or more
- 13a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 144a normal year
- Days that stay below freezing
- 54high of 32°F or less
- Days with 0.01 inch of precipitation
- 96a normal year
- Days with 1 inch of snow or more
- 10a normal year
The highest temperature in this station's record (since 1948) is 104°F, on June 21, 1988; the lowest is −27°F, on January 21, 1970.
The wettest calendar year on that record is 2014, with 46.19 in; the snowiest season is 1982–83, with 64.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00131277; records: ACIS (NOAA Regional Climate Centers), station USC00131277. Records use complete months only; a month missing more than three days is left out.
How sunny is Castana?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Castana, 4.1 kWh per square metre a day. July is the sunniest month (84%) and December the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 72% | 2.0 |
| February | 77% | 3.1 |
| March | 70% | 3.9 |
| April | 70% | 4.9 |
| May | 71% | 5.7 |
| June | 77% | 6.4 |
| July | 84% | 6.6 |
| August | 81% | 5.6 |
| September | 79% | 4.5 |
| October | 74% | 3.1 |
| November | 73% | 2.2 |
| December | 70% | 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 Castana need?
A normal year in Castana brings 6,879 heating degree days, 28% more than the median U.S. place (5,373), and 804 cooling degree days, 11% 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 3,036 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,412 | 0 |
| February | 1,152 | 0 |
| March | 895 | 1 |
| April | 509 | 5 |
| May | 203 | 48 |
| June | 26 | 174 |
| July | 4 | 274 |
| August | 12 | 209 |
| September | 115 | 83 |
| October | 440 | 11 |
| November | 858 | 0 |
| December | 1,254 | 0 |
| Year (annual) | 6,879 | 804 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00131277. 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 Castana been warmer than normal lately?
Over 53 complete years from 1951 to 2016, the station's annual mean temperature rose at a fitted 2.8°F per century (+0.15°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 Castana's climate compare?
Castana is warmer than 68 of the other 131 places with their own NOAA record in Iowa, and wetter than 18. Across the 7,247 U.S. stations with normals, its annual mean of 48.2°F is warmer than 33%.
In the Köppen classification computed from these normals, Castana 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 Castana share this climate record?
4 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.
- Ute, IA326 people · 7 mi E
- Moorhead, IA186 people · 10 mi S
- Soldier, IA176 people · 6 mi SE
- Turin, IA69 people · 7 mi SW
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 Castana's climate
What is the coldest month in Castana?
January, with a normal high of 29°F and a normal low of 10°F. The warmest is July (84°F by day, 64°F at night).
Does it snow in Castana?
Yes: 29 inches in a normal year, falling on 17 days with 0.1 inch or more, the most in February (7.2 inches).
What is the rainiest month in Castana?
June, with 4.84 in of precipitation in a normal year; the driest is January with 0.63 in.
What plant hardiness zone is Castana in?
The USDA's 2023 map puts Castana in zone 5b in ZIP code 51010, the nearest ZIP area. By the same method at Castana's NOAA station, the coldest night of a typical year reaches −14°F (27 years, 1991-2020): zone 5b.
How late can frost come in Castana?
In half of years the last 32°F night comes after April 25; in one year in ten it comes after May 7. Waiting until May 7 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Mapleton, IA7 miles from this station, 47.2°F a year
- Onawa, IA15 miles from this station, 48.5°F a year
- Little Sioux, IA20 miles from this station, 48.1°F a year
- Battle Creek, IA25 miles from this station, 46.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made