FleaDates › Tick season › California
Pacific · CA
When are ticks active in California?
California ticks don't take a real winter break: average temperatures stay above the ~40°F questing threshold in every month, with pressure heaviest Feb–Nov.
Ticks to know in California
California's tick clock runs opposite to what many owners expect: adult western blacklegged ticks are out in force during the cool, wet green-up, so coastal scrub, oak woodland, and shaded trail edges deserve attention long before summer. The nymphs, small enough to disappear in a thick coat, take over from late spring into summer, and pressure holds at its highest from May through October. American dog ticks work open grassland and brushy margins, while brown dog ticks favor hot inland homes and kennels, where an infestation can carry on entirely indoors.
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 California
| Month | Typical activity | Average temperature |
|---|---|---|
| January | Moderate | 51.9°F |
| February | High | 54°F |
| March | High | 56.8°F |
| April | High | 59.9°F |
| May | Peak | 64.5°F |
| June | Peak | 69°F |
| July | Peak | 72.7°F |
| August | Peak | 73°F |
| September | Peak | 70.9°F |
| October | Peak | 65.2°F |
| November | High | 57.3°F |
| December | Moderate | 51.6°F |
Estimates from NOAA U.S. Climate Normals (1991–2020), averaged across 5 weather stations near California'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. California flea season typically runs year-round — see the California flea season page.
Frequently asked questions
When does tick season start in California?
It never fully stops. California'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 Feb–Nov.
What ticks live in California?
The species dog owners most often meet in California: western blacklegged tick, American dog tick, brown dog tick. California's tick clock runs opposite to what many owners expect: adult western blacklegged ticks are out in force during the cool, wet green-up, so coastal scrub, oak woodland, and shaded trail edges deserve attention long before summer. The nymphs, small enough to disappear in a thick coat, take over from late spring into summer, and pressure holds at its highest from May through October. American dog ticks work open grassland and brushy margins, while brown dog ticks favor hot inland homes and kennels, where an infestation can carry on entirely indoors.
Do I need tick prevention in winter in California?
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 California?
Fleas run on a warmer calendar — in California that's year-round. See the California flea season page for that month-by-month picture.