Photo: AlphaBeta135 · CC BY 4.0Round Lake’s winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 83°, a January night drops to 15°, and about 43 inches of snow falls in a normal winter.
A year in Round Lake at a glance
Each month’s typical high and low, and what it brings.
What stands out about Round Lake’s climate
Compared with towns across the U.S., with Round Lake’s place in Illinois beside it.
What a year in Round Lake feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 162 frost-free days a year
In half of years the last 32° night comes by May 1 and the first by October 11. Frost and day counts come from NOAA’s station at Mc Henry -wg Stratton L&d, IL, 8 miles from the town’s center, at about the same height.
The 2023 USDA map puts Round Lake’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −11°. 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 43 inches of snow a winter
Snow, measured at Lake Villa 2ne, IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 37 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 126 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Round Lake
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 Mc Henry -wg Stratton L&d, IL.
Living with Round Lake’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
162 frost-free days in zone 5b. The last frost comes by May 1 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 11.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 1.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Round Lake from natural hazards, river flooding is the largest share (58%); heat waves, cold waves, winter storms and ice storms together are 19%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Round Lake and its neighbors
Every town next door is within a degree of Round Lake in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Round Lake’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 |
|---|---|---|---|---|
| Round Lake, IL | 15° | 83° | 37" | 43" |
| Elmira, NY | 16° | 83° | 36" | 42" |
| Albion, MI | 17° | 83° | 37" | 40" |
| Kendallville, IN | 17° | 83° | 38" | 36" |
| 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 Round Lake averaged 1.1° warmer than the 1900s. The biggest change is in December (+2.7°).
A smaller shift than in 68% 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 Round Lake compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Round Lake’s place among Illinois’.
Round Lake weather by month
Highs, lows and precipitation from NOAA’s grid at Round Lake’s center; snow, wet days and snow on the ground from Lake Villa 2ne, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 30° | 15° | 1.8" | 15.7" | 12 | 23 | 12° – 34° |
| February | 34° | 18° | 1.7" | 8.0" | 9 | 15 | 14° – 37° |
| March | 45° | 27° | 2.2" | 5.8" | 11 | 7 | 27° – 51° |
| April | 58° | 36° | 3.8" | 1.5" | 12 | 1 | 39° – 53° |
| May | 69° | 47° | 4.2" | 0.0" | 13 | 0 | 52° – 64° |
| June | 79° | 57° | 4.5" | 0.0" | 10 | 0 | 64° – 73° |
| July | 83° | 62° | 3.6" | 0.0" | 10 | 0 | 67° – 79° |
| August | 81° | 61° | 3.8" | 0.0" | 9 | 0 | 65° – 76° |
| September | 74° | 53° | 3.5" | 0.0" | 9 | 0 | 58° – 68° |
| October | 62° | 41° | 3.2" | 0.1" | 10 | 0 | 47° – 57° |
| November | 47° | 31° | 2.5" | 3.1" | 11 | 3 | 31° – 48° |
| December | 35° | 21° | 2.0" | 9.2" | 11 | 13 | 15° – 38° |
| Year | 58° | 39° | 36.9" | 43.4" | 126 | 61 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 27° to 51°. June is the most reliable, staying within 9°.
Where Round Lake’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 Round Lake’s center.
- Snow: Lake Villa 2ne, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Mc Henry -wg Stratton L&d, IL, 8 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 Round Lake’s climate
What is the weather like in Round Lake?
A typical July afternoon reaches 83°, a January night drops to 15°, and about 43 inches of snow falls in a normal winter. Colder January nights than 85% of U.S. towns; cooler July afternoons than 72% of U.S. towns.
How cold does it get in Round Lake in winter?
January nights average 15°. About 144 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 12°.
How much snow does Round Lake get?
About 43 inches in a normal winter at Lake Villa 2ne, IL, most of it in January, with snow on the ground about 61 days a year.
How hot does it get in Round Lake?
July, with a typical high of 83° and a low of 62°. About 11 days a year reach 90° (Mc Henry -wg Stratton L&d, IL).
When is the first and last frost in Round Lake?
In half of years the last spring frost (32°) comes by May 1 and the first fall frost by October 11, about 162 frost-free days, at Mc Henry -wg Stratton L&d, IL.
What growing zone is Round Lake in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −11°.
What is the best time of year to visit Round Lake?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Round Lake getting warmer?
Yes: 1991–2020 averaged 1.1° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 68% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Round Lake.
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.