How early should I schedule pest control for winter?

It's temperature, not a date on the calendar. House mice and other commensal rodents are documented to shift indoors as cooling temperatures make the outdoors more costly and food scarcer, and that shift accelerates around the first sustained cold snap of the season. In southern and central New Hampshire, that typically means late September into mid-October, with Manchester's average first hard frost landing between October 19 and 29. A specific date matters less than getting ahead of that transition.

The underlying biology here is genuinely real and sourced: cold reliably drives rodents toward structures, and sealing entry points before that pressure peaks measurably beats sealing them after. That's a real, honest do_this_first. What's marketing rather than mechanism is treating a specific date as a hard cutoff — as if pest control 'stops working' after October 15 or some similar line. It doesn't. Earlier is better on a sliding scale, because you're preventing entry into an empty structure rather than evicting an established one, but there's no date after which the fix stops being worth doing.

Mainly this: fewer rodents have already established themselves indoors by the time you seal, so the visit is prevention rather than eviction. It also overlaps with getting winter storage right — moving stored food and pet food into metal or glass before an unheated garage becomes an appealing, undisturbed shelter for months. Both are cheap, DIY-able fixes that are more effective the earlier they happen.