Frost dates for Rantoul, Illinois
Half of years have their last spring frost by April 21, but 1 year in 10 still frosts after May 6.
A frost date is really a percentile from 30 years of records at a nearby weather station: in about half of years a frost still comes after the median date. Both numbers are below, so you can choose the risk yourself.
The odds
Last spring frost
How often a frost still comes on or after each date.
- 1 year in 10
- May 6
- 1 year in 5
- May 1
- 3 years in 10
- April 27
- 2 years in 5
- April 24
- Half of years (the median)
- April 21
First fall freeze
How often the first freeze comes on or before each date.
- 1 year in 10
- October 5
- 1 year in 5
- October 10
- 3 years in 10
- October 12
- 2 years in 5
- October 15
- Half of years (the median)
- October 18
- Growing season
- about 179 days
- Hardiness zone nearby
- 6a
- Summer days
- a usual high of about 30 °C86 °F
- Lettuce and spinach run to seed
- May to September, in hot, long days (how we know)
Summer and rain
A growing garden needs about 25 mm1 in of water a week, rain and watering together. Here is what a normal month brings.
Month by month
- January
- high ~1 °C34 °F · low ~-9 °C16 °F · rain ~64 mm2.5 in
- February
- high ~4 °C40 °F · low ~-7 °C20 °F · rain ~51 mm2 in
- March
- high ~11 °C51 °F · low ~-2 °C29 °F · rain ~66 mm2.6 in
- April
- high ~18 °C64 °F · low ~4 °C40 °F · rain ~101 mm4 in
- May
- high ~24 °C75 °F · low ~11 °C51 °F · rain ~110 mm4.3 in
- June
- high ~29 °C85 °F · low ~16 °C62 °F · rain ~117 mm4.6 in
- July
- high ~31 °C87 °F · low ~18 °C64 °F · rain ~113 mm4.4 in
- August
- high ~30 °C86 °F · low ~16 °C62 °F · rain ~98 mm3.9 in
- September
- high ~27 °C81 °F · low ~12 °C54 °F · rain ~83 mm3.3 in
- October
- high ~20 °C67 °F · low ~6 °C42 °F · rain ~84 mm3.3 in
- November
- high ~11 °C52 °F · low ~0 °C31 °F · rain ~81 mm3.2 in
- December
- high ~4 °C40 °F · low ~-6 °C22 °F · rain ~56 mm2.2 in
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, the Rantoul station (listed by NOAA as Rantoul, USW00014806), at 40.31, -88.16. These are that station’s own records, unshifted. The further your garden is from it, the less exactly they describe your ground. The planner finds the nearest station to your garden and lowers its confidence with distance, so no number is presented as if it were measured in your garden.
Cold air also pools in low ground on the clear, still nights when frost happens, so a hollow can freeze while a slope a few hundred feet away does not. No table can know that about your garden. A few seasons of your own logged frosts can.
ZIP codes nearest this station
60932, 60933, 60936, 60948, 60949, 60957, 60960, 61724, 61770, 61801, 61802, 61812…
+17 moreShow fewer
61815, 61820, 61821, 61822, 61840, 61842, 61843, 61845, 61847, 61853, 61854, 61862, 61866, 61871, 61873, 61875, 61878.
Nearby stations
The nearest stations and how their last-frost dates compare. Together they show how frost varies across your area.
- Danville, IL, last frost by April 21
- Decatur Airport, IL, last frost by April 16
- Congerville 2 NW, IL, last frost by April 21
- Lowell, IN, last frost by April 29
- Peoria Greater Peoria Airport, IL, last frost by April 16
- Park Forest, IL, last frost by April 23
Other stations in Illinois.
- Springfield #2, IL, last frost by April 15
- Hennepin Wtr Trmt Plt, IL, last frost by April 24
- Aurora, IL, last frost by April 19
- Lisle-Morton Arboretum, IL, last frost by April 28
- Chicago Midway Airport, IL, last frost by April 11
- Hillsboro, IL, last frost by April 13
- Chicago Northerly Island, IL, last frost by April 10
- Carlinville, IL, last frost by April 14
When do I plant? · Where the dates come from
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