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Lawn Seeding Weather in Washington: Best Months by City

Lawn Seeding season in Washington, city by city: peak months, season boundaries, and annual workable-day counts from NOAA 1991–2020 normals. Kent leads with 299 workable days a year; Yakima runs the shortest at 123.

Washington is not one climate: Kent banks 299 workable lawn seeding days a year while Yakima gets 123 — a spread the table below itemizes month by month. Season boundaries mark the first and last month averaging 8+ workable days against the label rules (50–85°F, nights 32°F+).

If one month anchors the Washington calendar it's May, the statewide leader in workable days. Use this page to pick the month, then the city page's 10-day strip to pick the days — and the national lawn seeding guide for the physics behind each rule.

Cities in Washington

Peak months and season boundaries from NOAA 1991–2020 normals; season = months with at least 8 workable days.
CityPeak monthsSeasonWorkable days/yr
Seattle Mar, May, Jul February–November 295
Spokane May, Jun, Sep April–October 163
Kennewick May, Oct, Apr March–June 178
Bremerton Mar, May, Jul February–November 275
Tacoma Mar, May, Jul February–November 288
Olympia May, Jul, Aug March–November 243
Vancouver Mar, May, Jul February–November 297
Marysville May, Jul, Aug April–October 197
Bellevue Mar, May, Jul February–November 288
Yakima May, Sep, Jun April–June 123
Kent Mar, May, Jul February–November 299
Bellingham Mar, May, Jul February–November 279
Everett May, Jul, Aug March–November 256
Spokane Valley May, Jun, Sep April–October 163
Renton Mar, May, Jul February–November 288
Federal Way Mar, May, Jul February–November 288
Kirkland Mar, May, Jul February–November 280
Auburn Mar, May, Jul February–November 299
Wenatchee May, Oct, Apr March–June 171
Pasco May, Apr, Oct March–June 145

The rules behind these numbers

Typical label thresholds for lawn seeding — the single ruleset used by every check on this page.
CheckThresholdWhy it matters
Air temperature 50–85°F (low-temp formulas from 55°F) Cool-season grasses germinate best with daytime highs of roughly 60–80°F.
Overnight low ≥32°F during the first 48 h (≥40°F preferred) Seed survives a light frost, but sustained cold stalls germination.
Dry before no soaking (≥1.0") in the prior 24 h Seeding into mud makes ruts and washes seed into low spots.
Dry after <0.5" rain for 24 h after Light rain after seeding helps. A 0.5"+ downpour washes seed out.
Wind ≤15 mph (broadcast seed drifts up to 25 mph) Broadcast spreading above 15 mph lands seed everywhere but the lawn.

Always follow your product label — formulas vary. The table above is the typical range across major manufacturers, not a promise about your can.

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