Castleton (2 mi S), Indiana climate: Climate normals at a NOAA weather station
Castleton (2 mi S)'s normal year runs from 20°F January nights to 85°F July afternoons, with 47.2 inches of precipitation and 27 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.5°C, January lows of −7°C, July highs of 29°C, 1,198 mm of precipitation a year.
- NOAA stationCastleton (2 mi S)
- Station IDUSC00121326
- Location39.88°N 86.05°W
- Elevation824 ft (251 m)
On October 23, the normal high in Castleton (2 mi S) is 61°F and the normal low 42°F, and the chance of measurable rain or snow is 33%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Castleton (2 mi S).
- Jan 36° 20°
- Feb 41° 23°
- Mar 51° 32°
- Apr 64° 42°
- May 74° 52°
- Jun 82° 62°
- Jul 85° 65°
- Aug 83° 63°
- Sep 77° 56°
- Oct 65° 45°
- Nov 52° 34°
- Dec 40° 25°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Castleton (2 mi S) each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 20°F. The most precipitation falls in June (5.56 in), the least in February (2.66 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 36°F | 20°F | 27.8°F | 3.32 | 8.4 | 12 | <1 | 27 | 9 h 40 min |
| February | 41°F | 23°F | 31.6°F | 2.66 | 7.2 | 11 | <1 | 23 | 10 h 40 min |
| March | 51°F | 32°F | 41.7°F | 3.86 | 3.6 | 12 | <1 | 18 | 11 h 50 min |
| April | 64°F | 42°F | 53.1°F | 4.61 | 0.2 | 12 | <1 | 5 | 13 h 10 min |
| May | 74°F | 52°F | 62.9°F | 4.94 | 0.0 | 14 | 1 | <1 | 14 h 20 min |
| June | 82°F | 62°F | 71.8°F | 5.56 | 0.0 | 12 | 4 | <1 | 15 h |
| July | 85°F | 65°F | 74.9°F | 4.67 | 0.0 | 10 | 9 | <1 | 14 h 50 min |
| August | 83°F | 63°F | 73.1°F | 3.89 | 0.0 | 9 | 3 | <1 | 13 h 50 min |
| September | 77°F | 56°F | 66.3°F | 3.56 | 0.0 | 8 | 3 | <1 | 12 h 30 min |
| October | 65°F | 45°F | 54.5°F | 3.43 | 0.0 | 10 | <1 | 2 | 11 h 10 min |
| November | 52°F | 34°F | 42.6°F | 3.51 | 0.6 | 10 | <1 | 15 | 10 h |
| December | 40°F | 25°F | 32.6°F | 3.17 | 6.7 | 13 | <1 | 23 | 9 h 20 min |
| Year (annual) | 62°F | 43°F | 52.7°F | 47.18 | 26.7 | 134 | 19 | 113 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 2°C | −7°C | −2.3°C | 84 mm | 21 cm |
| February | 5°C | −5°C | −0.2°C | 68 mm | 18 cm |
| March | 11°C | 0°C | 5.4°C | 98 mm | 9 cm |
| April | 18°C | 6°C | 11.7°C | 117 mm | 1 cm |
| May | 23°C | 11°C | 17.2°C | 125 mm | 0 cm |
| June | 28°C | 17°C | 22.1°C | 141 mm | 0 cm |
| July | 29°C | 18°C | 23.8°C | 119 mm | 0 cm |
| August | 28°C | 17°C | 22.8°C | 99 mm | 0 cm |
| September | 25°C | 13°C | 19.1°C | 90 mm | 0 cm |
| October | 18°C | 7°C | 12.5°C | 87 mm | 0 cm |
| November | 11°C | 1°C | 5.9°C | 89 mm | 2 cm |
| December | 4°C | −4°C | 0.3°C | 81 mm | 17 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00121326; 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.
Which months are mildest at Castleton (2 mi S)?
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 USC00121326.
When is the last frost at Castleton (2 mi S)?
In Castleton (2 mi S), the last spring frost (32°F) comes after April 18 in half of years and after May 6 in one year in ten; the first autumn frost comes before October 26 in half of years and before October 12 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 181 year in 10 after May 6; 9 in 10 after April 3
- First autumn frost, half of years before
- October 261 year in 10 before October 12; 9 in 10 before November 7
NOAA puts the median frost-free season at 190 days, and the season without a hard freeze (28°F) at 213 days.
A hard freeze (28°F) comes after April 5 in half of springs and before November 5 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Castleton (2 mi S) in zone 6a in ZIP code 46250, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 6b: the coldest night of a typical year reaches −4°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 Indiana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00121326; 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 at Castleton (2 mi S)?
In a normal year in Castleton (2 mi S), 19 days a year reach 90°F (1 of them 100°F or more), 113 nights fall to 32°F or colder and 134 days bring measurable precipitation.
- Days at 90°F or more
- 19a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 113a normal year
- Days that stay below freezing
- 31high of 32°F or less
- Days with 0.01 inch of precipitation
- 134a normal year
- Days with 1 inch of snow or more
- 8a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00121326.
How sunny is it at Castleton (2 mi S)?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds at Castleton (2 mi S), 4.0 kWh per square metre a day. August is the sunniest month (81%) and December the cloudiest (59%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 61% | 1.8 |
| February | 63% | 2.6 |
| March | 66% | 3.7 |
| April | 71% | 4.8 |
| May | 72% | 5.5 |
| June | 79% | 6.3 |
| July | 80% | 6.1 |
| August | 81% | 5.5 |
| September | 80% | 4.6 |
| October | 73% | 3.2 |
| November | 69% | 2.2 |
| December | 59% | 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 many heating and cooling degree days does Castleton (2 mi S) record?
A normal year at Castleton (2 mi S) brings 5,428 heating degree days, 1% more than the median U.S. place (5,373), and 999 cooling degree days, 10% more 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 3,518 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,155 | 0 |
| February | 934 | 0 |
| March | 726 | 4 |
| April | 364 | 8 |
| May | 140 | 77 |
| June | 10 | 214 |
| July | 2 | 311 |
| August | 4 | 255 |
| September | 76 | 115 |
| October | 339 | 15 |
| November | 673 | 1 |
| December | 1,006 | 0 |
| Year (annual) | 5,428 | 999 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00121326. 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.
Have recent years at Castleton (2 mi S) been warmer than normal?
2025 averaged 53.0°F, 0.3°F above the 1991-2020 normal of 52.7°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 53.6°F | +0.9°F | 46.44 | 24.8 |
| 2022 | 52.5°F | −0.2°F | 38.85 | 17.9 |
| 2023 | 54.3°F | +1.6°F | 36.98 | 6.3 |
| 2024 | 55.2°F | +2.5°F | 49.29 | 16.1 |
| 2025 | 53.0°F | +0.3°F | 39.20 | 31.8 |
Source: observed years: ACIS, station USC00121326. A year counts only with all twelve months complete.
How does Castleton (2 mi S)'s climate compare?
Castleton (2 mi S) is warmer than 62 of the 99 places with their own NOAA record in Indiana, and wetter than 68. Across the 7,247 U.S. stations with normals, its annual mean of 52.7°F is warmer than 52%.
In the Köppen classification computed from these normals, Castleton (2 mi S) 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 Castleton (2 mi S) 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.
- Lawrence, IN49,817 people · 3 mi E
- McCordsville, IN11,744 people · 7 mi E
- Meridian Hills, IN1,779 people · 6 mi W
- Rocky Ripple, IN651 people · 7 mi W
- Williams Creek, IN429 people · 5 mi W
- Wynnedale, IN214 people · 9 mi SW
- Spring Hill, IN95 people · 8 mi SW
- Crows Nest, IN69 people · 6 mi W
- North Crows Nest, IN44 people · 6 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 Castleton (2 mi S)'s climate
What is the coldest month at Castleton (2 mi S)?
January, with a normal high of 36°F and a normal low of 20°F. The warmest is July (85°F by day, 65°F at night).
Does it snow at Castleton (2 mi S)?
Yes: 27 inches in a normal year, falling on 24 days with 0.1 inch or more, the most in January (8.4 inches).
What is the rainiest month at Castleton (2 mi S)?
June, with 5.56 in of precipitation in a normal year; the driest is February with 2.66 in.
What plant hardiness zone is Castleton (2 mi S) in?
The USDA's 2023 map puts Castleton (2 mi S) in zone 6a in ZIP code 46250, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −4°F (17 years, 1991-2020): zone 6b.
How late can frost come at Castleton (2 mi S)?
In half of years the last 32°F night comes after April 18; in one year in ten it comes after May 6. Waiting until May 6 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Indiana climateThe statewide normals and every place in the state
- Carmel, IN6 miles from this station, 51.6°F a year
- Beech Grove, IN11 miles from this station, 51.8°F a year
- Greenfield, IN17 miles from this station, 51.9°F a year
- Indianapolis, IN17 miles from this station, 53.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made