When is the last frost in Joliet, IL?

The average last spring frost (50% probability of 32°F) in Joliet is around April 19, based on NOAA/NCEI 1991–2020 normals at the Joliet Brandon Rd Dam, IL station (4.5 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Joliet?

The average first fall frost in Joliet, IL is around October 25, giving roughly a 188-day frost-free growing season.

What planting zone is Joliet, IL?

Joliet is in USDA plant hardiness zone 5b (average annual extreme minimum temperature -15 to -10°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Joliet?

In Joliet, IL the warmest month is July (avg high 83.6°F) and the coldest is January (avg low 16.6°F). It averages about 38″ of precipitation a year and 16.9″ of snow.

Home › Illinois › Joliet

Joliet, IL Planting Calendar & Frost Dates

USDA hardiness zone 5b · ZIP 60431 · elevation 166′ · NOAA & USDA data

Joliet is in USDA hardiness zone 5b (winters can dip to -15 to -10°F), with a growing season of about 188 days between the average last spring frost (April 19) and first fall frost (October 25). The warmest month is July (avg high 83.6°F); the coldest is January (avg low 16.6°F). It averages 38″ of precipitation a year and 16.9″ of snow, mostly mid-winter. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp -15 to -10°F

Last spring frost

April 19

avg (50% prob, 32°F)

First fall frost

October 25

avg (50% prob, 32°F)

Growing season

188 days

frost-free window

Warmest month

July

avg high 83.6°F

Month-by-month typical weather in Joliet

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Joliet Brandon Rd Dam, IL (4.5 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	31.1	16.6	23.9	2	5
February	35.4	19.8	27.6	1.8	6.2
March	47	29.2	38.1	2.3	2.1
April	59.9	38.9	49.4	3.9	0.1
May	71	49.4	60.2	4.5	0
June	80.3	59.9	70.1	4.3	0
July	83.6	64.1	73.9	4.6	0
August	81.8	62.9	72.3	4	0
September	76.2	55.3	65.7	3.2	0
October	63.3	43.4	53.3	3.1	0
November	48.5	32.3	40.4	2.5	0.3
December	36.4	22.4	29.4	1.9	3.2

What to plant when in Joliet

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 8 · Transplant out: April 26
Peppers	warm	Start seeds indoors: February 22 · Transplant out: May 3
Cucumbers	warm	Direct sow: April 26
Zucchini / squash	warm	Direct sow: April 26
Bush beans	warm	Direct sow: April 26
Sweet corn	warm	Direct sow: April 26
Basil	warm	Transplant out: April 26
Peas	cool	Sow (spring): March 15 · Sow (fall): August 30
Spinach	cool	Sow (spring): March 8 · Sow (fall): August 30
Lettuce	cool	Sow (spring): March 22 · Sow (fall): August 30
Kale	cool	Transplant (spring): March 29 · Sow (fall): August 16
Broccoli	cool	Transplant (spring): April 5
Carrots	cool	Sow (spring): March 29 · Sow (fall): August 16
Onions	cool	Transplant (spring): March 22
Potatoes	cool	Plant seed potatoes: April 5
Radishes	cool	Sow (spring): March 22 · Sow (fall): September 13

Dates are computed from Joliet's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

Want the exact dates for your yard? →
Look up your precise ZIP-code frost dates and a full 26-crop planting calendar on our free interactive tool.
Open the frost & planting tool

🌾 Get a frost reminder

One email in early spring and early fall with the dates for your area. No spam.

Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in Illinois

Plainfield, IL Romeoville, IL Bolingbrook, IL Aurora, IL Naperville, IL Orland Park, IL Tinley Park, IL Downers Grove, IL

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Joliet Brandon Rd Dam, IL, 4.5 mi (confidence: high). Monthly weather normals: Joliet Brandon Rd Dam, IL, 4.5 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.