Cairo 3N, IL Frost Dates & Growing Season

The two dates every Cairo 3N garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
Apr 2
~50% chance of frost after
First fall frost
Oct 31
~50% chance of frost before
Growing season
212 days
frost-free stretch
USDA zone
≈ 7a
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Mar 19 Apr 2 Apr 17
First fall frost Nov 13 Oct 31 Oct 18
Hard freeze (28°F), median last Mar 24 · first Nov 10

Computed from NOAA 1991–2020 climate normals at the CAIRO 3N station. "Safe" means frost past that date happens only about one year in ten. Your exact garden can still run days either way with elevation and terrain — check your own ZIP with the frost date lookup.

Planting windows for Cairo 3N

Computed from Cairo 3N's own frost dates. Click any crop for the full zone-7 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Feb 5 – Feb 19 Apr 9 – Apr 16
🫑 Peppers Jan 22 – Feb 5 Apr 16 – Apr 23
🥬 Lettuce Feb 19 – Mar 5 Mar 5 – Mar 19 Mar 5 – Apr 2
🫛 Peas Feb 19 – Mar 5
🥕 Carrots Mar 12 – Apr 2
🥦 Broccoli Feb 12 – Feb 26 Mar 12 – Mar 26
🥬 Kale Feb 19 – Mar 5 Mar 5 – Mar 19 Mar 5 – Mar 19
🥒 Cucumbers Mar 5 – Mar 12 Apr 9 – Apr 16 Apr 9 – Apr 16
🥒 Zucchini Mar 5 – Mar 12 Apr 9 – Apr 16 Apr 9 – Apr 16
🫘 Green Beans (Bush) Apr 9 – Apr 16
🌽 Sweet Corn Apr 9 – Apr 16
🌿 Basil Feb 19 – Mar 5 Apr 9 – Apr 16 Apr 16 – Apr 23
🧄 Garlic Fall: Sep 19 – Oct 17

Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Cairo 3N's dates automatically after a lookup.

Reading the season in Cairo 3N

With roughly 212 frost-free days, Cairo 3N gardens fit long-season crops — melons, winter squash, sweet potatoes — with room left for spring and fall rounds of greens and roots. The first frost around Oct 31 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Cairo 3N, IL?

The average last spring frost in Cairo 3N is around Apr 2, based on 1991–2020 climate normals. That's a median — about half of years see a later frost, so tender crops are safest going out a week or two after this date.

When is the first frost in Cairo 3N, IL?

The average first fall frost in Cairo 3N arrives around Oct 31. Crops still in the garden need to mature before then, and frost-tender plants need harvesting or protection as the date approaches.

How long is the growing season in Cairo 3N?

About 212 frost-free days on average, from Apr 2 to Oct 31. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Cairo 3N in?

USDA zone 7a on the 2023 Plant Hardiness Zone Map. Note that zones describe winter cold, not frost timing — these frost dates are the numbers to plan plantings around.