Olympia, WA Frost Dates
Published: February 1, 2026 · Updated: April 23, 2026
USDA Zone 4b
Last Spring Frost
May 7
Safe to transplant after this date
First Fall Frost
October 1
Protect tender plants before this date
Frost-Free Season
147 days
Early May to Late October
342 days until last frost in Olympia — May 7
Olympia’s location in USDA zone 4b creates one of the shorter growing seasons in the continental US. With a last spring frost of May 7 and first fall frost of October 1, the frost-free window is just 147 days — every gardening and lawn care decision must be precisely timed.
Complete Planting Calendar for Olympia
Lawn Care Timing for Olympia
Based on Olympia's USDA zone 4b frost dates: The last frost of May 7 marks when warm-season grasses begin recovering. Apply spring fertilizer in Early May when soil reaches 55°F. The first fall frost of October 1 sets your deadlines — complete overseeding by September 1–15 and apply winterizer by Late October.
USDA Zone 4b Summary
About 5 months frost-free. Classic cool-season lawn climate. Minneapolis, and similar northern cities.
Frequently Asked Questions
What is the last frost date in Olympia, WA?
The average last spring frost in Olympia is May 7. This is based on USDA zone 4b historical averages. Plan transplanting and spring lawn care around this date — wait 2 weeks after for frost-sensitive plantings.
When is the first fall frost in Olympia?
Olympia’s average first fall frost is October 1. This sets deadlines for fall overseeding (must be done 6 weeks before) and winterizer application (by Late October).
When should I plant tomatoes in Olympia?
Transplant tomato seedlings outdoors after May 7. Start seeds indoors Early March (8 weeks before last frost). Direct sow warm-season crops after may 15 (tomatoes, squash, beans).
When should I overseed my lawn in Olympia?
The prime overseeding window in Olympia is September 1–15. This ensures warm soil for germination before the first fall frost on October 1.
When should I apply winterizer in Olympia?
Apply winterizer fertilizer in Olympia by Late October. This high-potassium application hardens grass cell walls before freeze damage. Your first fall frost of October 1 is the hard deadline.