Photo: Ben Jacobson (Kranar Drogin) · CC BY 2.5Byron’s winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 84°, a January night drops to 13°, and about 32 inches of snow falls in a normal winter.
A year in Byron at a glance
Each month’s typical high and low, and what it brings.
What stands out about Byron’s climate
Compared with towns across the U.S., with Byron’s place in Illinois beside it.
What a year in Byron feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 174 frost-free days a year
In half of years the last 32° night comes by April 24 and the first by October 17. Frost and day counts come from NOAA’s station at Rockford Gtr Rockford Airport, 10 miles from the town’s center, at about the same height.
The 2023 USDA map puts Byron’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −14°. 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 32 inches of snow a winter
Snow, measured at Oregon, IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 38 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 88 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Byron
89% 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 Rockford Gtr Rockford Airport.
Living with Byron’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
174 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 17.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 30 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Byron from natural hazards, river flooding is the largest share (72%); heat waves, cold waves, winter storms and ice storms together are 11%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Byron and similar climates
TownRatings has no climate map of the towns around Byron yet.
Climates most like Byron’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 |
|---|---|---|---|---|
| Byron, IL | 13° | 84° | 38" | 32" |
| Grinnell, IA | 12° | 84° | 38" | 31" |
| Sayre, PA | 17° | 84° | 37" | 35" |
| Garrett, IN | 17° | 83° | 38" | 30" |
| Ghent, NY | 16° | 84° | 42" | 31" |
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 Byron averaged 1.2° warmer than the 1900s. The biggest change is in December (+2.5°).
A smaller shift than in 64% 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 Byron compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Byron’s place among Illinois’.
Byron weather by month
Highs, lows and precipitation from NOAA’s grid at Byron’s center; snow, wet days and snow on the ground from Oregon, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 29° | 13° | 1.6" | 13.6" | 7 | 11° – 34° |
| February | 34° | 17° | 1.7" | 6.7" | 6 | 12° – 37° |
| March | 47° | 28° | 2.4" | 3.0" | 7 | 29° – 52° |
| April | 60° | 37° | 3.8" | 0.8" | 8 | 40° – 55° |
| May | 71° | 49° | 4.4" | 0.0" | 10 | 54° – 66° |
| June | 81° | 58° | 5.2" | 0.0" | 9 | 66° – 74° |
| July | 84° | 62° | 4.0" | 0.0" | 7 | 67° – 79° |
| August | 82° | 60° | 4.0" | 0.0" | 7 | 65° – 77° |
| September | 75° | 52° | 3.6" | 0.0" | 7 | 58° – 69° |
| October | 63° | 41° | 2.9" | 0.0" | 7 | 47° – 58° |
| November | 47° | 30° | 2.4" | 1.5" | 6 | 30° – 48° |
| December | 34° | 19° | 2.0" | 6.7" | 7 | 13° – 37° |
| Year | 59° | 39° | 38.0" | 32.3" | 88 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 12° to 37°. June is the most reliable, staying within 8°.
Where Byron’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 Byron’s center.
- Snow: Oregon, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Rockford Gtr Rockford Airport, 10 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 Byron’s climate
What is the weather like in Byron?
A typical July afternoon reaches 84°, a January night drops to 13°, and about 32 inches of snow falls in a normal winter. Colder January nights than 89% of U.S. towns; cooler July afternoons than 63% of U.S. towns.
How cold does it get in Byron in winter?
January nights average 13°. About 136 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 11°.
How much snow does Byron get?
About 32 inches in a normal winter at Oregon, IL, most of it in January.
How hot does it get in Byron?
July, with a typical high of 84° and a low of 62°. About 15 days a year reach 90° (Rockford Gtr Rockford Airport).
When is the first and last frost in Byron?
In half of years the last spring frost (32°) comes by April 24 and the first fall frost by October 17, about 174 frost-free days, at Rockford Gtr Rockford Airport.
What growing zone is Byron in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −14°.
What is the best time of year to visit Byron?
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 Byron getting warmer?
Yes: 1991–2020 averaged 1.2° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 64% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Byron.
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.