Knox, Indiana climate: Normal weather by month, frost dates and records
Knox's normal year runs from 16°F January nights to 82°F July afternoons, with 42.2 inches of precipitation and 29 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.7°C, January lows of −9°C, July highs of 28°C, 1,072 mm of precipitation a year.
- NOAA stationKnox Wastewater Treatment Plant
- Station IDUSC00124657
- Location41.31°N 86.63°W
- Elevation690 ft (210 m)
- From the center1 miles
- Population3,630
On October 14, the normal high in Knox is 64°F and the normal low 43°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 Knox.
- Jan 32° 16°
- Feb 35° 18°
- Mar 47° 28°
- Apr 61° 38°
- May 71° 49°
- Jun 80° 59°
- Jul 82° 62°
- Aug 81° 60°
- Sep 74° 52°
- Oct 63° 42°
- Nov 49° 32°
- Dec 37° 22°
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 Knox each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 16°F. The most precipitation falls in June (4.65 in), the least in February (2.44 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 32°F | 16°F | 23.8°F | 2.73 | 9.7 | 12 | <1 | 29 | 9 h 30 min |
| February | 35°F | 18°F | 26.8°F | 2.44 | 7.5 | 10 | <1 | 26 | 10 h 40 min |
| March | 47°F | 28°F | 37.7°F | 2.53 | 3.4 | 10 | <1 | 23 | 11 h 50 min |
| April | 61°F | 38°F | 49.1°F | 3.75 | 0.2 | 12 | <1 | 10 | 13 h 20 min |
| May | 71°F | 49°F | 60.0°F | 4.45 | 0.0 | 12 | 1 | <1 | 14 h 30 min |
| June | 80°F | 59°F | 69.1°F | 4.65 | 0.0 | 11 | 2 | <1 | 15 h 10 min |
| July | 82°F | 62°F | 72.1°F | 4.35 | 0.0 | 10 | 3 | <1 | 14 h 50 min |
| August | 81°F | 60°F | 70.4°F | 4.48 | 0.0 | 9 | 1 | <1 | 13 h 50 min |
| September | 74°F | 52°F | 63.2°F | 3.47 | 0.0 | 9 | 1 | <1 | 12 h 30 min |
| October | 63°F | 42°F | 52.4°F | 3.59 | 0.0 | 10 | <1 | 4 | 11 h 10 min |
| November | 49°F | 32°F | 40.0°F | 3.17 | 2.0 | 10 | <1 | 18 | 9 h 50 min |
| December | 37°F | 22°F | 29.8°F | 2.61 | 5.7 | 12 | <1 | 27 | 9 h 10 min |
| Year (annual) | 59°F | 40°F | 49.5°F | 42.22 | 28.5 | 127 | 7 | 137 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 0°C | −9°C | −4.6°C | 69 mm | 25 cm |
| February | 2°C | −8°C | −2.9°C | 62 mm | 19 cm |
| March | 8°C | −2°C | 3.2°C | 64 mm | 9 cm |
| April | 16°C | 3°C | 9.5°C | 95 mm | 1 cm |
| May | 22°C | 10°C | 15.6°C | 113 mm | 0 cm |
| June | 27°C | 15°C | 20.6°C | 118 mm | 0 cm |
| July | 28°C | 17°C | 22.3°C | 110 mm | 0 cm |
| August | 27°C | 16°C | 21.3°C | 114 mm | 0 cm |
| September | 23°C | 11°C | 17.3°C | 88 mm | 0 cm |
| October | 17°C | 5°C | 11.3°C | 91 mm | 0 cm |
| November | 9°C | 0°C | 4.4°C | 81 mm | 5 cm |
| December | 3°C | −5°C | −1.2°C | 66 mm | 14 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00124657; 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 Knox?
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 (9).
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 USC00124657.
When is the last frost in Knox?
In Knox, the last spring frost (32°F) comes after April 26 in half of years and after May 12 in one year in ten; the first autumn frost comes before October 19 in half of years and before October 5 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 261 year in 10 after May 12; 9 in 10 after April 12
- First autumn frost, half of years before
- October 191 year in 10 before October 5; 9 in 10 before October 31
NOAA puts the median frost-free season at 174 days, and the season without a hard freeze (28°F) at 198 days.
A hard freeze (28°F) comes after April 15 in half of springs and before October 30 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Knox in zone 5b in ZIP code 46534, the nearest ZIP area.
Frost dates for every NOAA station in Indiana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00124657; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 Knox?
In a normal year in Knox, 7 days a year reach 90°F, 137 nights fall to 32°F or colder and 127 days bring measurable precipitation.
- Days at 90°F or more
- 7a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 137a normal year
- Days that stay below freezing
- 43high of 32°F or less
- Days with 0.01 inch of precipitation
- 127a normal year
- Days with 1 inch of snow or more
- 11a normal year
The highest temperature in this station's record (since 1897) is 100°F, on July 23, 1914; the lowest is −25°F, on January 17, 2009.
The wettest calendar year on that record is 2008, with 50.54 in; the snowiest season is 2007–08, with 66.4 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00124657; records: ACIS (NOAA Regional Climate Centers), station USC00124657. Records use complete months only; a month missing more than three days is left out.
How sunny is Knox?
Over a year 71% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Knox, 3.8 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (56%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 56% | 1.6 |
| February | 60% | 2.4 |
| March | 66% | 3.5 |
| April | 69% | 4.7 |
| May | 70% | 5.4 |
| June | 76% | 6.1 |
| July | 80% | 6.2 |
| August | 79% | 5.4 |
| September | 78% | 4.4 |
| October | 69% | 2.9 |
| November | 63% | 1.9 |
| December | 56% | 1.3 |
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 Knox need?
A normal year in Knox brings 6,298 heating degree days, 17% more than the median U.S. place (5,373), and 697 cooling degree days, 23% 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 2,926 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,275 | 0 |
| February | 1,070 | 0 |
| March | 848 | 1 |
| April | 481 | 4 |
| May | 206 | 51 |
| June | 29 | 153 |
| July | 8 | 229 |
| August | 15 | 181 |
| September | 123 | 67 |
| October | 401 | 11 |
| November | 749 | 0 |
| December | 1,093 | 0 |
| Year (annual) | 6,298 | 697 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00124657. 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 Knox been warmer than normal lately?
2025 averaged 49.7°F, 0.2°F above the 1991-2020 normal of 49.5°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 50.9°F | +1.4°F | 45.81 | 29.1 |
| 2022 | 47.8°F | −1.7°F | 39.34 | 28.0 |
| 2024 | 52.8°F | +3.3°F | 45.74 | 14.5 |
| 2025 | 49.7°F | +0.2°F | 40.33 | 34.8 |
Source: observed years: ACIS, station USC00124657. A year counts only with all twelve months complete.
How does Knox's climate compare?
Knox is warmer than 5 of the other 98 places with their own NOAA record in Indiana, and wetter than 41. Across the 7,247 U.S. stations with normals, its annual mean of 49.5°F is warmer than 38%.
In the Köppen classification computed from these normals, Knox 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 Knox share this climate record?
6 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.
- North Judson, IN1,814 people · 10 mi SW
- Bass Lake, IN1,067 people · 6 mi S
- Hamlet, IN780 people · 6 mi NE
- Hartz Lake, IN291 people · 11 mi SE
- Ora, IN136 people · 10 mi SE
- Groverton, IN121 people · 8 mi NE
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 Knox's climate
What is the coldest month in Knox?
January, with a normal high of 32°F and a normal low of 16°F. The warmest is July (82°F by day, 62°F at night).
Does it snow in Knox?
Yes: 29 inches in a normal year, falling on 17 days with 0.1 inch or more, the most in January (9.7 inches).
What is the rainiest month in Knox?
June, with 4.65 in of precipitation in a normal year; the driest is February with 2.44 in.
What plant hardiness zone is Knox in?
The USDA's 2023 map puts Knox in zone 5b in ZIP code 46534, the nearest ZIP area.
How late can frost come in Knox?
In half of years the last 32°F night comes after April 26; 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
- Indiana climateThe statewide normals and every place in the state
- Plymouth, IN16 miles from this station, 50.0°F a year
- Wanatah, IN18 miles from this station, 49.3°F a year
- Winamac, IN19 miles from this station, 50.1°F a year
- La Porte, IN22 miles from this station, 50.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made