FleaDates › Tick season › Oregon
Pacific · OR
When are ticks active in Oregon?
Oregon ticks don't take a real winter break: average temperatures stay above the ~40°F questing threshold in every month, with pressure heaviest Apr–Oct.
Ticks to know in Oregon
Western blacklegged ticks are the ones to know west of the Cascades, most numerous as adults during the cool, rainy stretch and waiting along brushy edges where trails meet oak and fir. Cross into the drier country east of the mountains and the cast shifts toward Rocky Mountain wood ticks in sagebrush and grassland, with American dog ticks common in open weedy ground on both sides of the state. Tick activity here never fully stops, though it runs strongest from June through September, when dogs are outside the longest.
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 Oregon
| Month | Typical activity | Average temperature |
|---|---|---|
| January | Moderate | 41.2°F |
| February | Moderate | 43.8°F |
| March | Moderate | 47.8°F |
| April | High | 52.1°F |
| May | High | 58.6°F |
| June | Peak | 64°F |
| July | Peak | 71°F |
| August | Peak | 71°F |
| September | Peak | 65.3°F |
| October | High | 55°F |
| November | Moderate | 45.9°F |
| December | Moderate | 40.5°F |
Estimates from NOAA U.S. Climate Normals (1991–2020), averaged across 3 weather stations near Oregon'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. Oregon flea season typically runs late March to early November — see the Oregon flea season page.
Frequently asked questions
When does tick season start in Oregon?
It never fully stops. Oregon's average temperatures sit above the ~40°F questing threshold all year, so tick checks and prevention are a twelve-month routine, with extra vigilance Apr–Oct.
What ticks live in Oregon?
The species dog owners most often meet in Oregon: western blacklegged tick, American dog tick, Rocky Mountain wood tick. Western blacklegged ticks are the ones to know west of the Cascades, most numerous as adults during the cool, rainy stretch and waiting along brushy edges where trails meet oak and fir. Cross into the drier country east of the mountains and the cast shifts toward Rocky Mountain wood ticks in sagebrush and grassland, with American dog ticks common in open weedy ground on both sides of the state. Tick activity here never fully stops, though it runs strongest from June through September, when dogs are outside the longest.
Do I need tick prevention in winter in Oregon?
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 Oregon?
Fleas run on a warmer calendar — in Oregon that's late March to early November. See the Oregon flea season page for that month-by-month picture.