When Do Mice Come Inside?
By Marcus Ellery, Pest Control Editor · Updated September 2026 · Methodology
House mice move toward buildings in the weeks when autumn nights start getting cold. There is no published temperature that flips the switch, so the useful marker is your first freeze: the window runs from the date one autumn in ten has already seen a 32°F night to the date a typical year gets one. Across the 6,948 NOAA weather stations that publish 1991-2020 freeze normals, that typical date ranges from August 21 at DELTA JUNCTION 20 SE, AK to February 1 at HEARST CASTLE, CA. Put your ZIP in below and you get your own dates.
Your window, by ZIP code
The nearest station with published freeze normals, how far away it is, and the dates. Nothing is extrapolated past 75 miles.
First-freeze windows in the cities we cover
Ordered by how early the typical first freeze arrives. Every station was matched to the city’s Census place point, and each is within eight miles of the city it represents.
| City | Migration window | Typical first freeze | Nights below 32°F |
|---|---|---|---|
| Madison, WI UW ARBORETUM - MADISON (3.2 mi) | September 26 to October 9 | October 9 | 157.4 |
| Minneapolis, MN LOWER ST ANTHONY FALLS (1.5 mi) | October 2 to October 16 | October 16 | 146.9 |
| Springfield, MO SPRINGFIELD WBO (0.6 mi) | October 15 to October 27 | October 27 | 89.1 |
| Knoxville, TN KNOXVILLE EXP STN (5 mi) | October 13 to October 28 | October 28 | 87.4 |
| Louisville, KY LOUISVILLE WFO (3.5 mi) | October 21 to November 1 | November 1 | 85.4 |
| Oklahoma City, OK OKLAHOMA CITY WILL ROGERS AP (7.3 mi) | October 21 to November 2 | November 2 | 72.2 |
| Chattanooga, TN CHATTANOOGA LOVELL AP (3.6 mi) | October 27 to November 9 | November 9 | 56.2 |
| Lubbock, TX LUBBOCK WFO (2.4 mi) | October 28 to November 11 | November 11 | 61.2 |
| Memphis, TN MEMPHIS INTL AP (3.8 mi) | November 2 to November 16 | November 16 | 44.4 |
| Pensacola, FL PENSACOLA RGNL AP (2.6 mi) | November 17 to December 9 | December 9 | 11.3 |
Source: NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal by station (fields ANN-TMIN-PRBFST-T32FP10 and P50, and ANN-TMIN-AVGNDS-LSTH032). Station matching uses the Census 2023 place gazetteer internal point.
What the 311 calls show
Freeze normals say when the weather turns. The other half of the question is whether people actually report more rodents then, so we pulled every city that publishes rodent complaints as open data, 2023 through 2026, and normalised each to its own year. A point at 8.3% would be an average month.
The answer came back against the assumption we started with. 5 of the 6 cities peak in summer, and in all six November carries a smaller share of the year than September does. Complaints are already falling by the time the first freeze lands. That is worth saying plainly, because the freeze window above and the curve below are measuring two different animals: a 311 rodent complaint is mostly somebody reporting outdoor rats, which peak in warm weather, while mice moving into a wall produces a call to an exterminator instead of to the city. We publish the mismatch rather than picking whichever series told a tidier story.
Each city counts a different thing, so these lines are only comparable in shape, never in level. Definitions and sources are on the rodent complaints hub.
What it costs once they are in
Trapping clears the mice that are already inside. Exclusion is the sealing work that decides whether you do this again next autumn. UC IPM calls exclusion the most successful and permanent form of house mouse control, and mice can get through a gap a quarter of an inch tall, so the sealing job is finer than most people expect.
| Job | 2026 national range |
|---|---|
| Inspection + trapping Mice & Rat Removal | $150 – $450 |
| Removal + exclusion (seal entry points) Mice & Rat Removal | $350 – $1,000 |
| Above + attic cleanup / decontamination Mice & Rat Removal | $600 – $2,000 |
| Inspection + trapping Rat Exterminator | $175 – $500 |
| Removal + exclusion (seal entry points) Rat Exterminator | $400 – $1,100 |
| Above + attic cleanup / decontamination Rat Exterminator | $700 – $2,000 |
Every figure is computed by the same estimator that powers the mice and rat calculator and the rat calculator. Planning ranges, researched from published cost guides, not lab-tested and not bids.
Frequently asked questions
Do mice come inside every winter?
Not every home, but the pressure is annual. House mice are active year round, and UC IPM notes that where outdoor populations exist they frequently enter homes in autumn when nighttime temperatures become colder. Whether they get in depends on your gaps, not on how cold it gets. A house with no opening larger than a quarter inch stays empty in the same weather that fills the house next door.
At what temperature do mice come indoors?
No extension source we could verify puts a number on it, and we will not invent one. The published guidance describes a direction rather than a threshold: mice move toward buildings as autumn nights get colder. That is why this page uses your first-freeze dates as the marker instead of a temperature trigger. The window runs from the date one autumn in ten has already had its first 32°F night to the date a typical year gets one.
How do I know whether it is mice or rats?
Size and droppings. Adult house mice are small and grey with droppings the size of a rice grain; roof and Norway rats are much larger and leave droppings closer to an olive pit. Mice can squeeze under a quarter-inch gap, so mouse entry points are often invisible until you look with a flashlight along the sill plate. Rats need a bigger opening and usually leave greasy rub marks along the route they use.
Does a cold winter kill them off?
No. Once mice are inside a heated building the outdoor temperature stops mattering, and they breed indoors through the winter. UC IPM reports a female house mouse may have five to ten litters of about five or six pups in a single year. A hard freeze pushes more of them toward your walls rather than fewer.
What does it cost if they are already in?
Trapping alone runs about $150 to $450. Removal plus exclusion, which is the sealing work that stops the next ones getting in, runs about $350 to $1,000. Add attic cleanup and the top of the range reaches $2,000. Those are national 2026 planning ranges from our calculator, not quotes.
Do city rodent complaints spike when the weather turns cold?
No, and we checked because we assumed they would. Across the 6 cities that publish 311 rodent data, 5 peak in summer, and in every one of the six November carries a smaller share of the year than September does. Complaints are falling by the time the first freeze arrives. A 311 rodent complaint is mostly an outdoor rat report, and outdoor rats are busiest in warm weather. Mice moving into a wall is a different event, and it produces a call to an exterminator rather than to the city, so 311 data does not see it. The freeze window on this page rests on the NOAA normals and the extension guidance, not on the complaint curve.
Sources
- UC Statewide IPM Program — Pest Notes: House Mouse (Publication 7483) for autumn entry, quarter-inch gaps, litter frequency, and exclusion.
- UC Statewide IPM Program — Pest Notes: Rats (Publication 74106) for rat behaviour indoors and rub marks.
- Internet Center for Wildlife Damage Management — House Mouse for year-round activity and autumn structure invasion.
- NOAA NCEI U.S. Climate Normals 1991-2020 for first-freeze probabilities and nights below 32°F.
- U.S. Census Bureau 2023 place gazetteer for the city points used in station matching.
- NYC Open Data — 311 Service Requests (2010 to Present) for New York City rodent complaints.
- Chicago Data Portal — 311 Service Requests for Chicago rodent complaints.
- Analyze Boston — 311 Service Requests for Boston rodent complaints.
- Open Data DC — 311 City Service Requests for Washington rodent complaints.
- Open Baltimore — 311 Customer Service Requests for Baltimore rodent complaints.
- City of Detroit Open Data — Improve Detroit Issues for Detroit rodent complaints.
Sealing before the freeze is the cheap version
The gap between trapping and trapping-plus-exclusion is roughly $300 on a typical job, and exclusion is the half that keeps next autumn quiet. Get the estimate, then get quotes.
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