January in Cortland bites harder than in 88% of U.S. towns
Midsummer highs settle at about 83°. Its July afternoons stay fresher than in 69% of U.S. towns. Compared with 1901–2000, the average now sits 1.1° higher. Long walks are most pleasant from May to October, when afternoons reach 62–83°.
A year in Cortland at a glance
Each month’s typical high and low, and what it brings.
What stands out about Cortland’s climate
Compared with towns across the U.S., with Cortland’s place in Illinois beside it.
What a year in Cortland feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 177 frost-free days a year
In half of years the last 32° night comes by April 24 and the first by October 18. Frost and day counts come from NOAA’s station at De Kalb, IL, 4 miles from the town’s center, at about the same height.
The 2023 USDA map puts Cortland’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −12°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 33 inches of snow a winter
Snow, measured at De Kalb, IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 38 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 121 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Cortland
90% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at De Kalb, IL.
Living with Cortland’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
177 frost-free days in zone 5b. The last frost comes by Apr 24 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 18.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 0.4 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Cortland from natural hazards, river flooding is the largest share (42%); heat waves, cold waves, winter storms and ice storms together are 34%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Cortland and similar climates
TownRatings has no climate map of the towns around Cortland yet.
Climates most like Cortland’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Cortland, IL | 14° | 83° | 38" | 33" |
| Grinnell, IA | 12° | 84° | 38" | 31" |
| Kendallville, IN | 17° | 83° | 38" | 36" |
| Sayre, PA | 17° | 84° | 37" | 35" |
| Charlotte, MI | 17° | 82° | 36" | 38" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Cortland averaged 1.1° warmer than the 1900s. The biggest change is in December (+2.3°).
A smaller shift than in 71% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Cortland compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Cortland’s place among Illinois’.
Cortland weather by month
Highs, lows and precipitation from NOAA’s grid at Cortland’s center; snow, wet days and snow on the ground from De Kalb, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 29° | 14° | 1.8" | 10.2" | 10 | 21 | 12° – 33° |
| February | 34° | 18° | 1.7" | 8.7" | 8 | 15 | 13° – 37° |
| March | 46° | 27° | 2.2" | 4.4" | 10 | 6 | 28° – 51° |
| April | 59° | 37° | 3.7" | 1.3" | 12 | 1 | 39° – 55° |
| May | 71° | 48° | 4.6" | 0.0" | 13 | 0 | 53° – 66° |
| June | 80° | 58° | 4.8" | 0.0" | 11 | 0 | 66° – 74° |
| July | 83° | 62° | 3.9" | 0.0" | 10 | 0 | 67° – 79° |
| August | 81° | 60° | 3.9" | 0.0" | 9 | 0 | 65° – 77° |
| September | 75° | 53° | 3.5" | 0.0" | 9 | 0 | 58° – 69° |
| October | 62° | 41° | 3.1" | 0.1" | 10 | 0 | 47° – 58° |
| November | 47° | 30° | 2.5" | 1.8" | 9 | 2 | 30° – 48° |
| December | 34° | 19° | 2.0" | 6.6" | 10 | 12 | 13° – 38° |
| Year | 58° | 39° | 37.7" | 33.1" | 121 | 57 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 13° to 37°. June is the most reliable, staying within 8°.
Where Cortland’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Cortland’s center.
- Snow: De Kalb, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: De Kalb, IL, 4 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Cortland’s climate
What is the weather like in Cortland?
A typical July afternoon reaches 83°, a January night drops to 14°, and about 33 inches of snow falls in a normal winter. Colder January nights than 88% of U.S. towns; cooler July afternoons than 69% of U.S. towns.
How cold does it get in Cortland in winter?
January nights average 14°. About 141 nights a year reach 32° or below and 12 reach 0° or below. In the coldest January of the last 30 years the month averaged 12°.
How much snow does Cortland get?
About 33 inches in a normal winter at De Kalb, IL, most of it in January, with snow on the ground about 57 days a year.
How hot does it get in Cortland?
July, with a typical high of 83° and a low of 62°. About 13 days a year reach 90° (De Kalb, IL).
When is the first and last frost in Cortland?
In half of years the last spring frost (32°) comes by April 24 and the first fall frost by October 18, about 177 frost-free days, at De Kalb, IL.
What growing zone is Cortland in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −12°.
What is the best time of year to visit Cortland?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Cortland getting warmer?
Yes: 1991–2020 averaged 1.1° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 71% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Cortland.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.