Weather without surprises: Dundas keeps close to the norm for U.S. towns
The coldest hours of a January night bottom out at 22° on average. The gap between a January night and a July afternoon is 65°. By precipitation alone, it ranks wetter than 63% of U.S. towns. Tender plants can go out after about April 15; in half of years the first frost comes by October 23.
A year in Dundas at a glance
Each month’s typical high and low, and what it brings.
What stands out about Dundas’ climate
Compared with towns across the U.S., with Dundas’ place in Illinois beside it.
What a year in Dundas feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 189 frost-free days a year
In half of years the last 32° night comes by April 15 and the first by October 23. Day counts come from NOAA’s station at Newton 6 Sse, IL, 6 miles from the town’s center, at about the same height; frost dates and degree days from Olney 2s, IL, 9 miles away.
The 2023 USDA map puts Dundas’ center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −3°. 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 14 inches of snow a winter
Snow, measured at Ste Marie (river), IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 46 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 101 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Dundas
81% of the work is heating. Months averaging under 55° run from November 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 Olney 2s, IL.
Living with Dundas’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
189 frost-free days in zone 6b. The last frost comes by Apr 15 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 23.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October.
Parks & trails →Of the yearly building losses FEMA expects in Dundas from natural hazards, river flooding is the largest share (44%); heat waves, cold waves, winter storms and ice storms together are 9%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Dundas and similar climates
TownRatings has no climate map of the towns around Dundas yet.
Climates most like Dundas’, 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 |
|---|---|---|---|---|
| Dundas, IL | 22° | 87° | 46" | 14" |
| Loveland, OH | 23° | 86° | 44" | 14" |
| Collegeville, PA | 23° | 88° | 47" | 13" |
| Bel Air North, MD | 24° | 87° | 47" | 18" |
| Millville, NJ | 25° | 87° | 46" | 12" |
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 Dundas averaged 0.8° warmer than the 1900s. The biggest change is in December (+1.8°).
A smaller shift than in 87% 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 Dundas compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Dundas’ place among Illinois’.
Dundas weather by month
Highs, lows and precipitation from NOAA’s grid at Dundas’ center; snow, wet days and snow on the ground from Ste Marie (river), IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 38° | 22° | 3.2" | 5.4" | 9 | 23° – 40° |
| February | 43° | 26° | 2.5" | 2.7" | 8 | 22° – 43° |
| March | 54° | 34° | 3.6" | 1.1" | 9 | 37° – 59° |
| April | 66° | 44° | 4.8" | 0.0" | 10 | 48° – 61° |
| May | 75° | 55° | 4.9" | 0.0" | 11 | 59° – 73° |
| June | 84° | 63° | 5.0" | 0.0" | 9 | 69° – 77° |
| July | 87° | 67° | 4.5" | 0.0" | 8 | 71° – 84° |
| August | 86° | 64° | 3.3" | 0.0" | 7 | 70° – 81° |
| September | 80° | 57° | 3.3" | 0.0" | 7 | 65° – 74° |
| October | 68° | 45° | 3.7" | 0.2" | 7 | 52° – 62° |
| November | 54° | 35° | 3.8" | 0.6" | 9 | 37° – 51° |
| December | 42° | 27° | 3.0" | 4.2" | 9 | 21° – 44° |
| Year | 65° | 45° | 45.6" | 14.2" | 101 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 21° to 44°. June is the most reliable, staying within 8°.
Where Dundas’ 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 Dundas’ center.
- Snow: Ste Marie (river), IL.
- Frost dates, heating and cooling: Olney 2s, IL, 9 miles away.
- Freezing nights, 90° and 100° days: Newton 6 Sse, IL, 6 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 Dundas’ climate
What is the weather like in Dundas?
A typical July afternoon reaches 87°, a January night drops to 22°, and about 14 inches of snow falls in a normal winter. Milder January nights than 51% of U.S. towns; hotter July afternoons than 61% of U.S. towns.
How cold does it get in Dundas in winter?
January nights average 22°. About 109 nights a year reach 32° or below and 3 reach 0° or below. In the coldest January of the last 30 years the month averaged 23°.
How much snow does Dundas get?
About 14 inches in a normal winter at Ste Marie (river), IL, most of it in January.
How hot does it get in Dundas?
July, with a typical high of 87° and a low of 67°. About 18 days a year reach 90° (Olney 2s, IL).
When is the first and last frost in Dundas?
In half of years the last spring frost (32°) comes by April 15 and the first fall frost by October 23, about 189 frost-free days, at Olney 2s, IL.
What growing zone is Dundas in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −3°.
What is the best time of year to visit Dundas?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Dundas getting warmer?
Yes: 1991–2020 averaged 0.9° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 87% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Dundas.
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.