Photo: Pdubs.94 · CC BY 4.0January in Rock Falls bites harder than in 88% of U.S. towns
July afternoons average 84°. It is a dry place: less rain and snow fall here than on 65% of U.S. towns. Compared with 1901–2000, the average now sits 1.3° higher. Radiators earn their keep from November to April, the months that average under 50°.
A year in Rock Falls at a glance
Each month’s typical high and low, and what it brings.
What stands out about Rock Falls’ climate
Compared with towns across the U.S., with Rock Falls’ place in Illinois beside it.
What a year in Rock Falls feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 180 frost-free days a year
In half of years the last 32° night comes by April 21 and the first by October 19. Frost and day counts come from NOAA’s station at Dixon 1w, IL, 10 miles from the town’s center, at about the same height.
The 2023 USDA map puts Rock Falls’ 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 29 inches of snow a winter
Snow, measured at Rock Falls 3 Ne, IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 39 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 109 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Rock Falls
88% 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 Dixon 1w, IL.
Living with Rock Falls’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
180 frost-free days in zone 5b. The last frost comes by Apr 21 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 19.
Months with highs of 62–84° and lows of 40° or more: May, June, August, September and October. 1.8 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Rock Falls from natural hazards, river flooding is the largest share (61%); heat waves, cold waves, winter storms and ice storms together are 15%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Rock Falls and its neighbors
Every town next door is within a degree of Rock Falls in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Rock Falls’, 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 |
|---|---|---|---|---|
| Rock Falls, IL | 14° | 84° | 39" | 29" |
| Osceola, IA | 13° | 85° | 37" | 28" |
| Auburn, IN | 17° | 84° | 38" | 30" |
| Claverack, NY | 16° | 84° | 42" | 31" |
| Sayre, PA | 17° | 84° | 37" | 35" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Rock Falls averaged 1.3° warmer than the 1900s. The biggest change is in December (+2.8°).
A smaller shift than in 51% 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 Rock Falls compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Rock Falls’ place among Illinois’.
Rock Falls weather by month
Highs, lows and precipitation from NOAA’s grid at Rock Falls’ center; snow, wet days and snow on the ground from Rock Falls 3 Ne, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 30° | 14° | 1.7" | 9.0" | 8 | 15 | 13° – 34° |
| February | 35° | 18° | 1.8" | 6.4" | 7 | 10 | 13° – 37° |
| March | 48° | 28° | 2.5" | 3.0" | 8 | 4 | 30° – 53° |
| April | 61° | 38° | 3.7" | 0.6" | 12 | 0 | 41° – 57° |
| May | 72° | 50° | 4.7" | 0.0" | 13 | 0 | 55° – 68° |
| June | 81° | 59° | 5.2" | 0.0" | 12 | 0 | 67° – 75° |
| July | 84° | 63° | 4.0" | 0.0" | 9 | 0 | 68° – 80° |
| August | 82° | 61° | 4.0" | 0.0" | 9 | 0 | 66° – 78° |
| September | 76° | 53° | 3.7" | 0.0" | 8 | 0 | 59° – 70° |
| October | 64° | 41° | 2.9" | 0.1" | 9 | 0 | 47° – 58° |
| November | 48° | 30° | 2.4" | 1.8" | 8 | 1 | 31° – 48° |
| December | 35° | 20° | 2.1" | 7.9" | 8 | 7 | 13° – 38° |
| Year | 60° | 40° | 38.5" | 28.8" | 109 | 38 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 13° to 38°. June is the most reliable, staying within 7°.
Where Rock Falls’ 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 Rock Falls’ center.
- Snow: Rock Falls 3 Ne, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Dixon 1w, IL, 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 Rock Falls’ climate
What is the weather like in Rock Falls?
A typical July afternoon reaches 84°, a January night drops to 14°, and about 29 inches of snow falls in a normal winter. Colder January nights than 88% of U.S. towns; cooler July afternoons than 58% of U.S. towns.
How cold does it get in Rock Falls in winter?
January nights average 14°. About 138 nights a year reach 32° or below and 13 reach 0° or below. In the coldest January of the last 30 years the month averaged 13°.
How much snow does Rock Falls get?
About 29 inches in a normal winter at Rock Falls 3 Ne, IL, most of it in January, with snow on the ground about 38 days a year.
How hot does it get in Rock Falls?
July, with a typical high of 84° and a low of 63°. About 11 days a year reach 90° (Dixon 1w, IL).
When is the first and last frost in Rock Falls?
In half of years the last spring frost (32°) comes by April 21 and the first fall frost by October 19, about 180 frost-free days, at Dixon 1w, IL.
What growing zone is Rock Falls 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 Rock Falls?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Rock Falls getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 51% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Rock Falls.
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.