When does blackfly season stop New Brunswick painting?

Blackfly season in New Brunswick typically winds down by late June to early July, which means exterior painting becomes significantly more pleasant — and practical — from early July through mid-October.

Blackflies in NB are most intense from mid-May through late June, peaking in the first three weeks of June. They thrive in cool, humid conditions near rivers and wooded areas, which describes a large portion of New Brunswick. If you're in the Saint John River Valley, Miramichi region, or anywhere near forested areas, you'll know exactly how miserable they make outdoor work.

How Blackflies Actually Affect Exterior Painting

It's not just about comfort. Blackflies (and to a lesser extent mosquitoes) can land in wet paint and leave marks, especially on trim, doors, and smooth surfaces where every imperfection shows. More practically, painters working in heavy blackfly conditions rush their work, skip careful cutting-in, and avoid the meticulous prep that a quality exterior job demands. A painter who's being swarmed is not doing their best work.

There's also the timing overlap to consider. Mid-May through late June is when NB wood siding and trim is still releasing spring moisture from snowmelt and heavy rain. Wood moisture content needs to be below 15% before you paint, and in May, many NB homes — especially older clapboard and cedar-sided houses — are still well above that threshold. So blackfly season and "too wet to paint" season overlap almost perfectly. Nature is essentially telling you to wait.

The Sweet Spot for Exterior Painting in NB

Early July through September is the ideal exterior painting window in New Brunswick. Blackflies are gone, wood has dried out from spring moisture, humidity is manageable in the mornings, and temperatures are consistently in the 15-25°C range — perfect for latex paint application and curing. September is particularly underrated: lower humidity than July and August, fewer insects, and excellent drying conditions.

If you're in northern NB — Bathurst, Edmundston, or the Restigouche area — keep an eye on overnight temperatures by late September, as early frost can arrive and catch fresh paint before it fully cures.

Practical Tips

Paint in the morning after dew has burned off (usually by 9-10am), and wrap up by early afternoon if humidity is climbing. Avoid painting in direct hot afternoon sun on south- and west-facing walls — it causes the paint to skin over too fast and traps solvent underneath.

If you're planning a full exterior repaint, booking a professional painter for July or August is smart, but those months fill up fast. Contact painters in May or June to get on their schedule for the summer season.

Need help finding a local exterior painting professional? New Brunswick Painting can match you with painters in your area for free — browse the directory at newbrunswickconstructionnetwork.com/directory?trade=painting.