When is the last frost in Bolingbrook, IL?

The average last spring frost (50% probability of 32°F) in Bolingbrook is around April 20, based on NOAA/NCEI 1991–2020 normals at the Romeoville Wfo, IL station (6.7 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 Bolingbrook?

The average first fall frost in Bolingbrook, IL is around October 22, giving roughly a 184-day frost-free growing season.

What planting zone is Bolingbrook, IL?

Bolingbrook is in USDA plant hardiness zone 6a (average annual extreme minimum temperature -10 to -5°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Bolingbrook?

In Bolingbrook, IL the warmest month is July (avg high 84.7°F) and the coldest is January (avg low 16.1°F). It averages about 41.1″ of precipitation a year and 33.2″ of snow.

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Bolingbrook, IL Planting Calendar & Frost Dates

USDA hardiness zone 6a · ZIP 60440 · elevation 201′ · NOAA & USDA data

Bolingbrook is in USDA hardiness zone 6a (winters can dip to -10 to -5°F), with a growing season of about 184 days between the average last spring frost (April 20) and first fall frost (October 22). The warmest month is July (avg high 84.7°F); the coldest is January (avg low 16.1°F). It averages 41.1″ of precipitation a year and 33.2″ 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 -10 to -5°F

Last spring frost

April 20

avg (50% prob, 32°F)

First fall frost

October 22

avg (50% prob, 32°F)

Growing season

184 days

frost-free window

Warmest month

July

avg high 84.7°F

Month-by-month typical weather in Bolingbrook

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Romeoville Wfo, IL (6.7 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	31.7	16.1	23.9	2.2	10.6
February	36.3	19.7	28	2	8.7
March	48.5	29.7	39.1	2.7	4.2
April	61	39.6	50.3	4.1	0.9
May	72.4	50.3	61.4	4.8	0
June	81.5	60.3	70.9	4.7	0
July	84.7	64.5	74.6	4.5	0
August	82.7	63	72.8	4.4	0
September	76.4	55.4	65.9	3.3	0
October	63.8	43.5	53.7	3.7	0.1
November	48.9	31.9	40.4	2.7	1.2
December	36.8	22	29.4	2.2	7.5

What to plant when in Bolingbrook

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 9 · Transplant out: April 27
Peppers	warm	Start seeds indoors: February 23 · Transplant out: May 4
Cucumbers	warm	Direct sow: April 27
Zucchini / squash	warm	Direct sow: April 27
Bush beans	warm	Direct sow: April 27
Sweet corn	warm	Direct sow: April 27
Basil	warm	Transplant out: April 27
Peas	cool	Sow (spring): March 16 · Sow (fall): August 27
Spinach	cool	Sow (spring): March 9 · Sow (fall): August 27
Lettuce	cool	Sow (spring): March 23 · Sow (fall): August 27
Kale	cool	Transplant (spring): March 30 · Sow (fall): August 13
Broccoli	cool	Transplant (spring): April 6
Carrots	cool	Sow (spring): March 30 · Sow (fall): August 13
Onions	cool	Transplant (spring): March 23
Potatoes	cool	Plant seed potatoes: April 6
Radishes	cool	Sow (spring): March 23 · Sow (fall): September 10

Dates are computed from Bolingbrook'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.

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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

Romeoville, IL Naperville, IL Downers Grove, IL Aurora, IL Plainfield, IL Wheaton, IL Lombard, IL Orland Park, 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 — Romeoville Wfo, IL, 6.7 mi (confidence: high). Monthly weather normals: Romeoville Wfo, IL, 6.7 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.