April through October, give or take, with a big nymph wave in May, June, and July. Adult ticks pick up again in the fall. Each species has its own shape and each province its own timing, drawn from what Canadians have reported over the past 2 years.
Short answer
Threshold
4°C
Most ticks need ground temperatures above about 4°C to be active. That’s usually early April in southern Ontario and the Maritimes, mid-April further north.
The dangerous wave
May, June, and July
Blacklegged nymphs are the size of a poppy seed and the life stage responsible for most Canadian Lyme cases. Peak activity is late spring and early summer.
Late season
October
Adult blacklegged ticks come back in fall and stay active into November in mild years. Tick season isn’t over the day school starts.
Sightings by month
When Canadians are finding ticks.
2,871 sightings reported between September 2024 – September 2026, grouped by species. The bars track the rough shape of each species’ year: when they start moving, when they peak, and when they quiet down.
Blacklegged
American dog
RM wood
Lone Star
Right now, where you are
Check today's risk for your province.
Pick a species, a province and a month. The dial combines the time of year with how established that species is in your province.
Current reading
Low
Quiet this month. Still do a tick check after time outdoors.
Based on published seasonal activity patterns and where each species is established.
By province
Where the season is right now.
Each strip is one province’s 12 months of sightings, January on the left. Taller bars mean more ticks reported that month. Busiest provinces first.
Ontario
n = 1,925
Nova Scotia
n = 339
Manitoba
n = 184
Quebec
n = 124
British Columbia
n = 53
Saskatchewan
n = 51
New Brunswick
n = 33
Alberta
n = 25
Prince Edward Island
n = 5
The one that bites kids
The poppy-seed nymph window.
Blacklegged nymphs (poppy-seed size) cause most Canadian Lyme cases. They’re small enough to miss on a tick check and they peak in May, June, and July. If your kids spend time in long grass, leaf litter or forest edges, late May to early July is the window to take seriously.
Adult blacklegged ticks are sesame-seed size and much easier to spot. They’re more common in early spring and again in the fall. Both stages can carry Lyme, but an adult on a person tends to get found quickly.
When can you stop?
The season's late edge.
Tick checks aren’t a summer-only thing. Adult blacklegged ticks quest (climb a blade of grass and wait for a host) on any day the ground is unfrozen and above about 4°C. That can mean late November in a mild fall or early March in an early spring. If you’re hiking in a t-shirt, the ground is warm enough for ticks.
Ticks go fully dormant once ground temperatures stay below 4°C for weeks at a stretch, typically December through February across most of Canada. Winter activity is still possible in the southernmost parts of Ontario and on the BC coast.