Do squirrels hibernate?

No. Eastern gray squirrels are homeotherms that maintain a steady body temperature and stay active year-round; only ground squirrels and chipmunks enter true hibernation. Because tree squirrels never go dormant, a squirrel that has moved into your attic can be legally and humanely evicted even in the middle of January, per Indiana DNR — timing exclusion just needs to avoid the two annual litter windows.

When do squirrels get into attics?

Attic entry surges twice a year: in fall, as squirrels scatter-hoard food and seek warm shelter ahead of Manchester's ~Oct 19 first frost, and again just before each of the two breeding seasons, when females look for a secure nest site. Expect the biggest spikes around the Dec–Feb and Jun–Aug litter periods, per Affordable Wildlife Control. An attic mimics a warm tree cavity almost perfectly, which is why it's such a strong draw once outdoor temperatures start dropping toward frost.

When do squirrels breed?

Gray squirrels breed twice a year — a late-winter season roughly December through February, and a summer season roughly May/June through August. Gestation runs about 44 days, producing 2–4 young per litter, though younger females may have only one litter a year, according to Illinois DNR. Each breeding season drives a fresh wave of attic-nesting activity as females look for secure den sites.

I hear scratching in my attic during the day — what is it?

Daytime attic noise strongly points to squirrels, which are diurnal and most active in the early morning and late afternoon with a midday rest. That timing distinguishes them from nocturnal raccoons, rats, mice, and bats, which move at night. If the scratching happens after dark instead, a different nocturnal animal is more likely responsible, so noting the time of day is one of the fastest ways to narrow down which species you're dealing with before scheduling an inspection.

Is a squirrel out in daylight a rabies risk?

No. Squirrels are naturally daytime-active animals, so seeing one during the day is completely normal behavior, not a sign of rabies or illness. This is different from nocturnal mammals like raccoons, where daytime activity combined with disorientation or aggression can be a warning sign. A squirrel foraging in your yard at noon is simply doing what gray squirrels do — the actual warning signs to watch for are stumbling, paralysis, or unprovoked aggression, none of which are typical squirrel behavior.

Why are squirrels so frantic in fall?

Fall is scatter-hoarding season: squirrels bury thousands of individual nuts and seeds across their territory to rely on through winter. During this period they eat an estimated 30% more than they need and add roughly 25% to their body weight in fat reserves, per JP Pest Services and A-Z Animals. That frantic burying and eating is also when attic-entry risk climbs sharply ahead of the first frost.

Are squirrels most active in the morning or evening?

Both — gray squirrels show two daily activity peaks, one in the early morning and another in the late afternoon, with a quieter midday rest in between. This pattern holds year-round, though winter cold can push them to stay in the nest for extended stretches during the harshest days before resuming their normal dawn-and-dusk foraging routine. If you hear activity in an attic at midday specifically, it's more likely a brief wake-up than a full return to normal foraging.

Can you remove a squirrel from an attic in winter?

Yes. Because gray squirrels never enter true hibernation, an attic squirrel remains active and can be excluded in winter using one-way doors and heavy wire mesh, not chicken wire. The one caution is timing around dependent young — avoid sealing a female in with non-mobile kits during the Dec–Feb or Jun–Aug litter windows, and confirm the space is empty first.

Daniel Brady · NH-Licensed Pesticide Applicator · License #782664

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Where Do Squirrels Go in the Winter? NH Timing Guide

Overwintering Wildlife

Squirrels stay in New Hampshire year-round and remain active through winter rather than hibernating. They shelter in leaf-nest dreys, tree cavities, or attics — which mimic warm tree hollows — and survive on nuts they scatter-hoarded in fall, extra body fat, a thicker coat, and shared body heat. During extreme cold they may stay in the nest for several consecutive days, then re-emerge to feed. Because they never go dormant, attic squirrels can be legally and humanely excluded even in the dead of winter, as long as no dependent young are present.

At a glance

Activity pattern: DiurnalMost active early morning and late afternoon; does not hibernate — Illinois DNR / Indiana DNR
Winter strategy: Homeotherm, no hibernationScatter-hoards nuts, adds ~25% body weight in fall (eats an estimated ~30% more than needed), grows a thicker coat, shares dreys — JP Pest Services / A-Z Animals
Breeding: Two seasons: late winter (Dec–Feb) + summer (Jun–Aug)Gestation ~44 days; 2–4 young per litter — Illinois DNR
Peak attic-entry: Fall + just before each birthing seasonCaching and shelter-seeking drive the surge — Affordable Wildlife Control

Activity pattern
Diurnal
Most active early morning and late afternoon; does not hibernate — Illinois DNR / Indiana DNR
Winter strategy
Homeotherm, no hibernation
Scatter-hoards nuts, adds ~25% body weight in fall (eats an estimated ~30% more than needed), grows a thicker coat, shares dreys — JP Pest Services / A-Z Animals
Breeding
Two seasons: late winter (Dec–Feb) + summer (Jun–Aug)
Gestation ~44 days; 2–4 young per litter — Illinois DNR
Peak attic-entry
Fall + just before each birthing season
Caching and shelter-seeking drive the surge — Affordable Wildlife Control

The timing answer

The short of it

The verdict · overwintering wildlife

Active all winter (diurnal)

Eastern gray squirrels do NOT hibernate — they stay active every winter day in New Hampshire, living on cached nuts in dreys, tree cavities, and often attics.

NH activity calendar

When are they active — the whole year at a glance

Gray squirrels are active every month in New Hampshire. The calendar below tracks the two annual breeding peaks and the fall caching/attic-entry surge that drives most homeowner calls.

12-month activity · New Hampshire

Peak · Jan, Feb, Jun, Oct, DecYou are here · Aug

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

PeakActiveBuildingDecliningDormantCurrent season · Summer

Best window to act · Early fall before the frost-driven surge, or late fall once fall young are mobile — always outside the two breeding windows (late Feb–Mar and Jun–Aug).

What else peaks thenJan Feb Jun Oct Dec

Peaks track the two birthing seasons (Dec–Feb and Jun–Aug) and the fall caching/attic-entry surge, anchored to Manchester's ~Oct 19 first hard frost (50% probability, NOAA 1991–2020).

Where they go in winter

Winter behavior

The most common question about squirrels is where they go once it turns cold. The honest answer: nowhere. They don't leave and they don't sleep it off.

Overwintering strategy

Active all winter

Squirrels don't leave. They stay active in leaf-nest dreys, tree cavities, and often attics — which mimic warm tree hollows — living on scatter-hoarded nuts, extra fat, thicker fur, and shared body heat.

Move in
Fall (caching and shelter-seeking ahead of the ~Oct 19 first frost) and again just before each breeding season.
Active all winter
Squirrels don't leave. They stay active in leaf-nest dreys, tree cavities, and often attics — which mimic warm tree hollows — living on scatter-hoarded nuts, extra fat, thicker fur, and shared body heat.
Spring exit
There is no true exit — squirrels are active year-round. Winter-litter juveniles disperse March–April, and attic females may relocate their young after both the Dec–Feb and Jun–Aug litters.

Season by season

A year in the life

Squirrel behavior shifts through the New Hampshire year, but the animals themselves never go dormant.

01
Spring
Winter-litter juveniles disperse and begin foraging on their own, while adults switch to buds and early greenery as cached nuts run low. Sightings climb noticeably as young squirrels explore.
02
Summer
The second breeding peak (roughly June–August) brings a fresh round of attic nesting as females seek secure den sites for a new litter. Juveniles from spring are fully independent by mid-summer.
03
Fall
The highest-risk season for homeowners. Squirrels scatter-hoard thousands of nuts and seek warm shelter ahead of the frost, driving the year's biggest surge in attic entry — this is the best exclusion window if no young are present.
04
Winter
Squirrels remain fully active, relying on caches, added body fat, and a thicker coat. During extreme cold they may stay in the drey for several days at a stretch, then emerge to feed — meaning an attic squirrel can still be evicted even in January.

New Hampshire context

Squirrels in southern New Hampshire

Eastern gray squirrels are everywhere in Manchester, Nashua, and Concord neighborhoods, wherever mature trees meet rooflines. Because they never truly hibernate, NH's long, cold winters make attics — which trap heat like a tree cavity — one of the most attractive den sites in the region, especially once the fall scatter-hoarding season collides with falling temperatures.

Key local data

First hard frost in Manchester averages October 19 (50% probability), the point at which fall caching and attic-entry sharply accelerate — NOAA 1991–2020.

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When to act

Timing your treatment

Because squirrels never go dormant, timing an exclusion is about avoiding the two litter windows, not waiting out winter.

The right window

Early fall before the frost-driven surge, or late fall once fall young are mobile — always outside the two breeding windows (late Feb–Mar and Jun–Aug).

Daytime scratching or scampering in the attic, especially early morning

Chewed electrical wires — a fire risk

Gnawed holes in the soffit, fascia, or gable vents

A suspected nesting female with dependent young

Visible drey traffic leading to the roofline

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Learn more about this pest

Common Questions

Frequently asked

Sources & references

Illinois Department of Natural Resources — Eastern Gray Squirrel
diurnal activity pattern, breeding seasons, gestation and litter size
Indiana Department of Natural Resources — Gray Squirrel
no true hibernation, homeotherm biology
JP Pest Services — Eastern Gray Squirrel
scatter-hoarding, fall fat gain, shared dreys
A-Z Animals — Do Grey Squirrels Hibernate?
winter activity, fat and coat changes
Affordable Wildlife Control — Do Squirrels Hibernate in Attics?
peak attic-entry timing
Squirrels at the Feeder — Do Squirrels Hibernate?
winter drey behavior, cold-weather dormancy bouts
Garden.org — Frost Dates, Manchester NH (NOAA 1991–2020)
Manchester first hard frost ~Oct 19

Editorial disclaimer: This content is provided for informational purposes only and does not constitute pest control advice. Every property is unique — consult a licensed professional for guidance specific to your situation. Anchor Pest Services is licensed in New Hampshire (#782664).

Written & reviewed by

Verified

Daniel Brady

NH-Licensed Pesticide Applicator · License #782664 (NHDAMF, RSA 430)

Daniel Brady is the New Hampshire–licensed applicator behind Anchor Pest Services, a family-owned pest control company serving the Manchester area since 2017.

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Last updated Jul 2026

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Keep Exploring

Where Do Squirrels Go in the Winter? NH Timing Guide

The short of it

When are they active — the whole year at a glance

Winter behavior

A year in the life

Spring

Summer

Fall

Winter

Squirrels in southern New Hampshire

Timing your treatment

Frequently asked

Sources & references

Whatever the season — we handle the timing for you.

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Where Do Squirrels Go in the Winter? NH Timing Guide

The short of it

When are they active — the whole year at a glance

Winter behavior

A year in the life

Spring

Summer

Fall

Winter

Squirrels in southern New Hampshire

Timing your treatment

Frequently asked