FleaDates › Tick season › Washington
Pacific · WA
When are ticks active in Washington?
Ticks in Washington are typically active mid-February to late November, heaviest May–Sep — and adult blacklegged ticks can surface on any mild winter day.
Ticks to know in Washington
West of the Cascades, the western blacklegged tick is the main concern along ferny, brushy forest edges; east of the crest, Rocky Mountain wood ticks emerge early as the snow pulls back and are the species behind tick paralysis in dogs. American dog ticks fill in along open grassy trails in both halves of the state. Pressure builds through spring and peaks from June into September, so a full check after a hike in the Cascades or the Palouse — ears, neck, armpits, groin — is worth the two minutes.
Wherever the calendar sits this month, the habit that actually catches ticks is the after-walk check: ears, collar line, armpits, between the toes. Prevention plus checks beats either alone.
Month-by-month tick activity in Washington
| Month | Typical activity | Average temperature |
|---|---|---|
| January | Low | 34.7°F |
| February | Low | 37.7°F |
| March | Moderate | 43.5°F |
| April | Moderate | 49.5°F |
| May | High | 57.6°F |
| June | Peak | 63.3°F |
| July | Peak | 70.3°F |
| August | Peak | 69.7°F |
| September | Peak | 62°F |
| October | Moderate | 50.5°F |
| November | Moderate | 40.2°F |
| December | Low | 33.9°F |
Estimates from NOAA U.S. Climate Normals (1991–2020), averaged across 3 weather stations near Washington's larger cities, using the ~40°F activity threshold reported in published tick research. Real years run early or late with the weather.
Fleas peak later. Washington flea season typically runs early April to late October — see the Washington flea season page.
Frequently asked questions
When does tick season start in Washington?
Around mid-February in a typical year, once temperatures clear roughly 40°F — noticeably earlier than flea season. A February thaw can bring ticks out ahead of schedule.
What ticks live in Washington?
The species dog owners most often meet in Washington: western blacklegged tick, Rocky Mountain wood tick, American dog tick. West of the Cascades, the western blacklegged tick is the main concern along ferny, brushy forest edges; east of the crest, Rocky Mountain wood ticks emerge early as the snow pulls back and are the species behind tick paralysis in dogs. American dog ticks fill in along open grassy trails in both halves of the state. Pressure builds through spring and peaks from June into September, so a full check after a hike in the Cascades or the Palouse — ears, neck, armpits, groin — is worth the two minutes.
Do I need tick prevention in winter in Washington?
Yes. Ticks overwinter under leaf litter and snow rather than dying off, and mild spells wake them — which is why veterinary organizations recommend year-round parasite prevention. The calendar shows when pressure peaks, not when protection can lapse.
What about fleas in Washington?
Fleas run on a warmer calendar — in Washington that's early April to late October. See the Washington flea season page for that month-by-month picture.