St. Lawrence County, New York

What hazards hit St. Lawrence County most?

The most frequent records are winter storm records: 641 since 1996. 49% of its winter storm records since 1996 fell in January and February. The rank column places the county among New York's counties by days with a record per 1,000 square miles of land over each hazard's complete period.

Source: NOAA NCEI Storm Events Database (county and forecast-zone records attributed to the county; a zone record shows its own totals on each county it covers). Days: dates with at least one record of the hazard in the county. Ranks: days with a record per 1,000 square miles of land (Census Bureau 2024 Gazetteer), since 1950 for tornadoes, 1955 for hail and thunderstorm wind, 1996 for the rest.

How many tornadoes has St. Lawrence County had?

NOAA records 11 tornadoes in St. Lawrence County from 1954 to 2026, the strongest rated F2, with 1 death and 4 injuries recorded in the county. A tornado that crossed a county line is counted in each county it touched, with the length of its path inside the county.

Counted as whole tornadoes rather than county records, the Storm Prediction Center's database holds 11 tornadoes whose track touched St. Lawrence County since 1950 (NOAA's county records number 11, the same count); along their whole tracks they killed 1 person.

Map of the strongest tornado tracks in New York.

Source: NOAA NCEI Storm Events Database, tornado records by county (path length in the county, maximum width); ratings as published: F scale before February 1, 2007, EF scale after. Whole-track figures: NOAA Storm Prediction Center tornado database (1950-2025). SPC severe weather database.

When was the last damaging storm in St. Lawrence County?

The most recent record with damage, injuries or deaths is the June 30, 2026 thunderstorm wind ($10,000 in damage in 2025 dollars).

Source: NOAA NCEI Storm Events Database; every record of 2025-2026 is listed, earlier ones when they caused deaths, injuries or $250,000 of damage (2025 dollars), and every tornado.

The deadliest and costliest records

A damage figure marked "step" is a record from before 1993: NOAA then filed damage by category, and the figure is the category as entered, in the dollars of that year, not an estimate of the loss.

Source: NOAA NCEI Storm Events Database: deaths and injuries direct and indirect; damage is property plus crops as estimated by the National Weather Service, converted to 2025 dollars.

Is it getting more frequent?

Records per decade for St. Lawrence County's most frequent hazards. Counts rose everywhere after 1996, when NOAA began recording every event type, so compare decades within a hazard's complete period only (the shaded cells come before it).

Extreme cold in the 2020-26: 26 records against 8 in the decade before, 26 of them forecast-zone records. Cells marked z rose mostly through zone records. The local National Weather Service office files these once per forecast zone, so a change in how it draws its zones or splits a storm into records moves this count as much as the weather does; read it beside the St. Lawrence County days with a record above.

Source: NOAA NCEI Storm Events Database, records per calendar decade; zone records from the CZ_TYPE field (Z).

What time of year?

49% of its winter storm records since 1996 fell in January and February. The two busiest months are in violet.

Source: NOAA NCEI Storm Events Database, records by the month they began.

Federal disaster declarations for St. Lawrence County

FEMA's register lists 19 declarations that include St. Lawrence County: 11 major disasters, 8 emergencies and 0 fire management assistance declarations. Most were for snowstorm (6) and flood (3).

Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), declarations through October 2, 2026; one declaration is counted once however many areas it names. OpenFEMA dataset page.

How many floods has St. Lawrence County had?

NOAA's Storm Events Database holds 35 flood or flash flood records for St. Lawrence County from 1996 to 2024, on 28 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), St. Lawrence County ranks 1329th of 2,942 U.S. counties.

The National Flood Insurance Program has paid $1.7 million on 95 claims filed in St. Lawrence County; the most in one year was 13 in 1998. Claims count insured losses only: uninsured flood damage is not in this file.

Source: FEMA OpenFEMA NFIP Redacted Claims, as of September 8, 2026; claims by year of loss, payments in the dollars of the year paid. OpenFEMA dataset page.

FEMA's modeled risk for St. Lawrence County

FEMA's National Risk Index rates St. Lawrence County Relatively Low overall, with an expected annual loss of $31.9 million. These are FEMA's model estimates of future loss from 18 hazards, not a count of what happened; they can differ from the record above.

Source: FEMA National Risk Index, county table, December 2025 release. FEMA's National Risk Index map.

Counties that share a border with St. Lawrence County

1. Herkimer County 1,800
2. St. Lawrence County 1,346
3. Franklin County 1,001
4. Lewis County 774
5. Jefferson County 699
6. Hamilton County 636

Source: U.S. Census Bureau county adjacency file; NOAA NCEI Storm Events Database, records since 1950. The Census Bureau's adjacency file.

Next

• Tornadoes in New YorkEvery New York tornado since 1950 and the counties with the most per square mile
• Winter storms in New YorkThe state's winter storm records, by county, year and month
• The New York recordEvery hazard in the state, its deadliest events and its federal declarations
• FEMA's risk rating for each hazard in St. Lawrence CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download St. Lawrence County's FEMA declarations (CSV)19 rows: every declaration that named the county, for your own analysis