Allegany County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Allegany County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every storm within 100 miles

1. Tropical storms and hurricanes (34 kt or more, still tropical) at closest approach. Post-tropical remnants with gale-force winds are listed but not counted. Direct: track within 50 miles; near: within 100 miles. Distance is measured to the county boundary for counties and to the city centre for cities, using positions interpolated hourly between HURDAT2 fixes.

National Hurricane Center HURDAT2, 1851 to 2025.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

Mapped landslides

Mapped by USGS Conterminous (1).

1. Landslides mapped in the USGS compilation of landslide inventories across the United States (version 3.0, 2025), rated probable or better. The compilation joins inventories made by federal and state agencies for different purposes and areas, so the number mapped in a county reflects how closely it has been surveyed as much as how often its slopes fail. An area with few records may simply not have been mapped. Deaths are as recorded in the inventories; a slide listed in two inventories is counted once.

USGS Landslide Inventories across the United States, version 3.0, retrieved October 27, 2026.

More event types since 1996

Costliest events since 1996

1. Jul 23, 2003Flash Flood$7.0 million
   National Weather Service narrative

   For the third day in a row, thunderstorms dumped heavy rains on the western southern tier. More flash flooding occurred on area creeks and streams. Roads were washed out or undermined. Several bridges were washed out or damaged. Damage was reported in New Albion, Hinsdale, Olean, Cuba, Allegany, Belmont and Belfast.

2. Aug 9, 2003Flash Flood$2.0 million
   National Weather Service narrative

   Strong thunderstorms developed in a very moist atmosphere, dropping three to five inches of rain in a short amount of time onto already saturated ground. The heavy rains produced flash flooding over parts of the southern tier and Finger Lakes. In Livingston county, the Towns of Nunda and Sparta were hardest hit. A reservoir line, which provides water to Nunda's water treatment plant, was damaged. An earthen dam on the 50-million-gallon drinking water reservoir was damaged. Families living below the dam were evacuated as a precaution. Many miles of roads and road shoulders were damaged, along with several bridges and culverts. In Cattaraugus county, the town of Ischua sustained…

3. Apr 26, 2011Flash Flood$1.2 million
   National Weather Service narrative

   A line of showers and thunderstorms crossed the area during the evening hours. The thunderstorms were accompanied by strong winds, large hail and intense rains. The winds downed trees and wires on Whig hill and one inch hall fell in Scio. Following an extremely wet spring, any rain the fell on the saturated ground became runoff. The two to three inches of rainfall resulted flash flooding in Allegany and Ontario counties. In Wellsville, two to three feet of water washed across the streets with over a dozen streets closed or washed out. In Allegany county, damage was also reported in Alfred, Andover, Angelica, Granger, West Almond and Friendship. In Ontario county, basements were…

4. Aug 5, 2003Flash Flood$1.0 million
   National Weather Service narrative

   Thunderstorms during the afternoon hours produced several inches of rain over parts of the southern tier to the Finger Lakes region. The heavy rains fell on already saturated ground from storms over the past several weeks. Rainfalls of over an inch and a half in a half hour were reported. In Allegany county, the heavy rains again caused flash flooding and road closures over an area already hard hit and damaged by flooding in July. State Routes 417 and 19 were closed as culverts overflowed. In Ontario county, the towns of Honeoye, East Bloomfield, Bristol, Naples and Richmond were affected by flooding. Several roads were washed out and debris and tree limbs were littered throughout…

5. Jan 19, 1996Flood, Allegany$1.0 million
   National Weather Service narrative

   Rapid snowmelt of 1-2 feet of snow combined with heavy rainfall of over two inches to produce significant flooding. Nearly four hundred homes were damaged by flood waters. There were road closures and evacuations in Wellsville. Power and municipal water supplies were cut for several hours.

6. Nov 22, 2000Heavy Snow, Allegany$1.0 million
   National Weather Service narrative

   Cold air crossing the warm waters of Lakes Erie and Ontario resulted in lake effect squalls that dropped over two feet downwind of the lakes.Off Lake Erie, the squall developed around midday on the 20th in a southwest flow ahead of a cold front. Snow fell at the rate of two to four inches per hour for several hours. The storm crippled much of the Buffalo metro area. Tens of thousands of people were stranded in autos as city and suburban streets became clogged with traffic and came to a standstill. Three thousand school children were stranded in buses which were unable to complete their routes. Snowfall in this early stage were as high as two feet in a narrow strip about three…

7. Aug 5, 2003Flash Flood$1.0 million
   National Weather Service narrative

   Thunderstorms during the afternoon hours produced several inches of rain over parts of the southern tier to the Finger Lakes region. The heavy rains fell on already saturated ground from storms over the past several weeks. Rainfalls of over an inch and a half in a half hour were reported. In Allegany county, the heavy rains again caused flash flooding and road closures over an area already hard hit and damaged by flooding in July. State Routes 417 and 19 were closed as culverts overflowed. In Ontario county, the towns of Honeoye, East Bloomfield, Bristol, Naples and Richmond were affected by flooding. Several roads were washed out and debris and tree limbs were littered throughout…

8. Aug 9, 2000Flash Flood$750,000
   National Weather Service narrative

   Numerous thunderstorms crossed the western southern tier and genesee valley during the evening hours. The thunderstorm winds downed trees and power lines. Thousands were without electricity. The torrential rains accompanying the thunderstorms, coming just a few days after earlier heavy rains, resulted in flash flooding...especially in Allegany county. Hardest hit was Centerville, Hume, Granger and Caneadea. Several towns in the western southern tier declared States of Emergency. Damage to roads was extensive. In Allegany county, Routes 23, 27, 36 and 3 were closed for days.

9. Sep 9, 2004Flood, Allegany$630,000
   National Weather Service narrative

   Western and central New York were inundated by drenching rains as the remnants of hurricane Frances drifted north across the region on Thursday September 9th. Areawide rainfall totaled 3 to 5 inches with the bulk of it falling in a 6 to 9 hour period from very late Wednesday to midday Thursday. Several creeks in the Buffalo and Rochester areas recorded their greatest flows and highest gage levels ever in a non-winter/spring season. Cazenovia Creek at Ebenezer was above the 10 foot flood stage from 6AM to 8PM Thursday the 9th, cresting at 14.85 feet. Buffalo Creek at Gardenville was above the 7 foot flood stage from 9AM to 8PM Thursday the 9th, cresting at 8.71 feet. Cayuga Creek…

10. Dec 29, 2001Heavy Snow, Allegany$500,000
    National Weather Service narrative

    Lake effect snowbands shifted into the western southern tier area late on the 28th and persisted through the 30th. Specific storm totals included: in Chautauqua county: Arkwright 56"; Sherman 48"; Sinclairville 30"; Fredonia 28"; Ellington 25"; Dunkirk 22" and Silver Creek 20". In Cattaraugus county: South Dayton 54"; Perrysburg 51"; Yorkshire 46" and New Albion 21". In Allegany county: Rushford 15" and Angelica 11".

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

104°FJul 11, 1936

All-time low

−40°FFeb 9, 1934

Warmest night

76°FAug 12, 1918

Coldest day

−7°FFeb 8, 1895

Wettest day

4.50 inJul 6, 1902

Snowiest day

22.0 inDec 25, 1978

Hottest year

2012mean 50.3°F

Coldest year

1917mean 41.9°F

Wettest year

201848.74 in

Driest year

194121.88 in

Snowiest season

114.5 in1893-94

Station Angelica (USC00300183), 1,475 ft elevation, 5.7 miles from the population centre. Daily records from 1893 to October 21, 2026; 96.0% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USC00300183.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Landslides USGS Landslide Inventories across the United States, version 3.0 (2025).
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.