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Lawn Seeding Weather in Colorado: Best Months by City

Lawn Seeding season in Colorado, city by city: peak months, season boundaries, and annual workable-day counts from NOAA 1991–2020 normals. Lakewood leads with 156 workable days a year; Longmont runs the shortest at 90.

Across Colorado's 17 listed cities, annual workable days for lawn seeding run from 90 (Longmont) up to 156 (Lakewood). Every number comes from NOAA 1991–2020 normals scored against the same label ruleset; every city name links to its live 10-day check.

If one month anchors the Colorado 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 Colorado

Peak months and season boundaries from NOAA 1991–2020 normals; season = months with at least 8 workable days.
CityPeak monthsSeasonWorkable days/yr
Denver May, Sep, Jun April–June 103
Colorado Springs May, Sep, Jun April–June 143
Aurora May, Sep, Jun April–June 103
Fort Collins May, Sep, Jun April–June 136
Lakewood May, Jun, Sep April–June 156
Thornton May, Sep, Oct April–June 101
Grand Junction May, Apr, Oct April–May 112
Greeley May, Sep, Oct April–June 101
Arvada May, Sep, Jun May–June 108
Pueblo May, Sep, Oct April–May 99
Boulder May, Sep, Jun April–June 124
Westminster May, Sep, Oct April–June 101
Centennial May, Sep, Jun April–June 132
Longmont May, Sep, Jun May–June 90
Highlands Ranch May, Sep, Jun April–June 132
Lafayette May, Sep, Oct April–June 101
Castle Rock May, Jun, Sep August–October 140

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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