Rodent Complaints in Boston: Where and When (2023–2026 311 Data)

Complaints by month, 2023 to 2026

September, October and November are shaded so you can see how the autumn months sit against the rest of the year in Boston.

One caveat about the Boston data

Boston publishes one file per calendar year rather than a single rolling dataset, so each year is fetched separately. The bigger caveat is geographic: a ZIP is present on about seven records in ten, so the ZIP table below counts noticeably fewer cases than the citywide monthly totals. Both figures are correct for what they measure, and neither should be read as the other. Boston is also the only city in this set whose three-year trend runs upward.

Reading the Boston numbers

Boston spreads its rodent complaints across 30 ZIP codes, and the load is not spread evenly. The busiest five carry 35% of the three-year total and the busiest ten carry 62%. ZIP 02127 alone logged 1,023 complaints, about 2.3 times the median ZIP code in the city. Adjusting for size changes the picture: 02113 runs the densest at about 3360.7 complaints per square mile across 0.1 square miles, even though it sits at rank 18 on raw volume.

Across the year, August (13.45%), July (12.52%) and September (11.41%) are the three heaviest months, while February (4.17%), January (4.67%) and December (5.61%) are the three lightest. May through October alone accounts for roughly 66% of a Boston year. Year to year the totals ran +27.7% into 2024, then +4.5% into 2025. 2026 stands at 4,080 through September.

Every month, in full

The raw counts behind the charts above, so you can check our arithmetic against Analyze Boston — 311 Service Requests yourself.

Average share is the mean of each full calendar year’s monthly share, so a heavy year cannot dominate the seasonal curve. The 2026 column is incomplete by design.

The 25 busiest ZIP codes in Boston

Totals cover 2023 through 2025, the three full calendar years in the window. Per square mile uses the Census ZCTA land area, which is what makes a small dense ZIP comparable to a large one.

30 ZIP codes recorded at least one complaint. Volume tracks reporting behaviour as well as rodent activity: a block that knows how to use 311 shows up more than an identical block that does not.

Freeze dates for Boston

The nearest NOAA station publishing 1991–2020 first-freeze normals is BOSTON LOGAN INTL AP, 1.6 miles from the city point. One autumn in ten sees its first 32°F night by October 29; a typical year gets one around November 9; nine years in ten have had one by November 22. The station averages 91.6 nights a year below freezing.

We went into this expecting complaints to climb toward the first freeze. In Boston they do not. Boston complaints peak in August, and by November the month carries 4.57 percentage points less of the year than September did, with the typical first freeze still landing in November. We publish the gap rather than smoothing it. The likeliest reason is that a 311 rodent complaint is mostly an outdoor rat report, and outdoor rat activity runs highest in warm weather, while the autumn move indoors is house mouse behaviour that rarely becomes a city service request. Somebody with mice behind a kitchen cabinet calls an exterminator, not the city.

What removal costs if it is your house

National 2026 planning ranges from our estimator, not Boston quotes.

Frequently asked questions

Sources

• Analyze Boston — 311 Service Requests — dataset 311-service-requests, filtered on case_title ILIKE '%Rodent Activity%', extracted September 9, 2026.
• NOAA NCEI U.S. Climate Normals 1991–2020 — station USW00014739, BOSTON LOGAN INTL AP.
• U.S. Census Bureau 2023 ZCTA gazetteer — ZIP land area used for the per-square-mile column.
• UC Statewide IPM Program — Pest Notes: Rats (Publication 74106) — rat behaviour and exclusion.