Iowa Frost Dates
Published: February 1, 2026 · Updated: April 23, 2026
Last Spring Frost
April 7
Zone 5b
First Fall Frost
October 22
Zone 5b
Frost-Free Season
198 days
Early April to Early November
Lawn Care Timing for Iowa
Vegetable Garden Timing for Iowa
Frost Dates by City in Iowa
Frequently Asked Questions
What is the last frost date in Iowa?
The average last spring frost in Iowa (zone 5b) is April 7. Dates vary by city and elevation. Find your specific city below for exact dates.
When is it safe to plant tomatoes in Iowa?
Transplant tomato seedlings outdoors after April 7 — the average last frost date for zone 5b. Start seeds indoors Late January. Wait 2 weeks after last frost for extra safety.
When should I overseed my lawn in Iowa?
The prime overseeding window in Iowa is August 20–September 20. This ensures 6 weeks of warm soil for germination before the first fall frost on October 22.
When should I apply winteriser in Iowa?
Apply winteriser fertiliser by Early November. Your first fall frost of October 22 is the hard deadline — apply at least 2–3 weeks before.
What USDA zone is Iowa?
Iowa contains USDA zones 5b. Each zone has different frost dates and growing seasons. Find your city below for your specific zone.