The short answer: April through October, give or take, with a big nymph wave in May, June, and July. Adult ticks pick back up again in the fall. Below: the month-by-month picture for each species and a per-province breakdown drawn from what Canadians have reported over the past two 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.
2,151 sightings reported between May 2024 – May 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 reads the same activity curves behind the chart above, weighted by how established each species is in your part of Canada.
Current reading
Low
Activity is quiet this month. Tick checks are still worth doing.
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 twelve months of sightings, left to right (January → December). Taller bars mean more ticks reported in that month. Provinces sorted by total activity.
Ontario
n = 1,507
Nova Scotia
n = 193
Manitoba
n = 124
Quebec
n = 87
British Columbia
n = 51
Saskatchewan
n = 34
New Brunswick
n = 33
Alberta
n = 25
Prince Edward Island
n = 4
The one that bites kids
The poppy-seed nymph window.
Blacklegged nymphs — the size of a poppy seed — are responsible for most Canadian Lyme cases. They’re small enough to miss on a tick check, and they peak in May, June, and July. If you have kids who spend time in long grass, leaf litter, or forest edges, the late-May-to-early-July window is the one to take seriously.
Adult blacklegged ticks — the size of a sesame seed, much easier to spot — are more common in early spring and again in the fall. Both stages can carry Lyme, but an adult tick 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 on any day the ground is unfrozen and above about 4°C — which can mean late November in a mild fall and early March in an early spring. If you’re hiking in a t-shirt, the ground is warm enough for ticks.
True dormancy comes when ground temperatures stay below 4°C for stretches of weeks — typically December through February across most of Canada, though winter activity is possible in the southernmost parts of Ontario and on the BC coast.
Prevention — repellents, treated clothing, and tick checks.
Sightings drawn from eTick.ca and iNaturalist Canada submissions over the past two years. Typical activity curves derived from Public Health Agency of Canada (PHAC) and provincial public-health unit reports.
Last reviewed
General information only — not medical advice. In an emergency, call 911. Read the full disclaimer.
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