Union County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Union County: 2.
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.

Costliest events since 1996

1. Jun 20, 1996Thunderstorm Wind$15.0 million
   National Weather Service narrative

   Strong winds knocked trees down along Rte. 80 near West Buffalo Township.

2. Sep 7, 1999Flash Flood$10.0 million
   National Weather Service narrative

   The city of Lewisburg was especially hard hit by the remnants of Hurricane Dennis as up to 8 inches of rain fell in 24 hours, most of it during the early morning hours. Waters rose rapidly in the early morning hours. At least 160 people were displaced from their homes, many of them Bucknell University students. A total of 414 homes were affected by the flooding along with 30 county businesses. Vehicles were floated down the city side streets and 162 were damaged. The campus of Bucknell University also had damage. Other parts of the county from Mifflinburg east to the Susquehanna River had problems. Route 15, the major north/south highway to Harrisburg, was closed due to flooding.

3. Sep 7, 2011Flood$800,000
   National Weather Service narrative

   The West Branch Susquehanna River at Lewisburg crested in moderate flood stage at 25.91 feet. Flood stage is 18.0 feet. This was the 11th all time highest crest. The West Branch Susquehanna River at Milton crested in major flood stage at 26.6 feet. Flood stage is 19.0 feet. This is the 10th all time highest crest. The West Branch of the Susquehanna River at Watsontown crested in moderate flood stage of 26.7 feet. Flood stage is 20.0 feet. This is the 8th highest crest all time.||Several roads in Union County were closed due to flooding from creeks and streams, resulting from heavy rainfall from the remnants of Tropical Storm Lee. Flooding was reported on the West Branch of the…

4. Jun 7, 1999Thunderstorm Wind$150,000
   National Weather Service narrative

   Downburst winds took the roof off the St John's Lutheran Church near Kellys Crossroads 3 miles west of Milton. Three barns also had roof damage and trees were down across the area.

5. Apr 14, 2019Tornado$100,000
   National Weather Service narrative

   The National Weather Service in State College PA confirmed an EF1 tornado near Buffalo Valley in East Buffalo Township in Union County Pennsylvania on April 15, 2019.||Initial straight line wind damage was surveyed at Melmar Drive, where large trees were uprooted. Straight line downburst winds accelerated down the hillside to the north of Melmar Drive causing the tornado to spin up just before reaching the Buffalo Valley United Methodist Church (the former Buffalo Cross Roads Elementary School), where trees were uprooted in a convergent pattern along the path.||The tornado continued northeast, completely destroying a barn and snapping/uprooting additional trees along Buffalo Road…

6. Aug 20, 1999Flash Flood$100,000
   National Weather Service narrative

   Six to eight inches of rain fell in 3 hours & caused serious flooding across eastern parts of the county.

7. Sep 4, 2001Tornado$60,000
   National Weather Service narrative

   An F1 tornado touched down in Kelly Township, about 2 NW of Lewisburg on Colonel John Kelly Road. The tornado traveled to the southeast, remaining north of Lewisburg. It crossed Route 15 and eventually the Susquehanna River, crossing into Northumberland County. A Township building in Kelly township was destroyed, with significant damage to a township truck. 13 utility poles were snapped off, in addition to 75 to 100 trees. Winds were estimated to be around 80 mph, classifying the tornado as a weak F1. There were no injuries or deaths.

8. Apr 23, 1996Thunderstorm Wind$50,000
   National Weather Service narrative

   Trees fell on a car and a home in Lewisburg

9. Aug 20, 2015Tornado$40,000
   National Weather Service narrative

   An EF1 tornado was confirmed by an NWS survey team just south of Mifflinburg in Union County. A large shed was destroyed and a roof was partially torn off of a barn. Peak winds were estimated at 90 mph, classifying this as an EF1.

10. Jul 2, 2023Tornado$40,000
    National Weather Service narrative

    A tornado touched down in West Buffalo Township during the afternoon of July 2, 2023. Initial touchdown was in a field just west of Pleasant Grove Road, and the tornado tracked adjacent to Dietrich Road towards Pine Valley Trailer Park where some minor damage was observed to outer buildings. The tornado continued northeastward towards the intersection of Church Road and Clark Avenue where garage door collapsed inward and a roof was lifted off. The tornado dissipated just south of a bend in Church Road. The tornado was rated an EF-1, with a path length of just over 2 miles and a max path width of approximately 50 yards.

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

103°F3 times, most recently Jul 22, 2011

All-time low

−20°FJan 21, 1994

Warmest night

78°FJul 15, 1995

Coldest day

0°FJan 17, 1982

Wettest day

8.66 inJun 22, 1972

Snowiest day

20.0 inFeb 19, 1972

Hottest year

2024mean 54.3°F

Coldest year

1965mean 48.4°F

Wettest year

201170.26 in

Driest year

199730.08 in

Snowiest season

85.9 in1995-96

Station Williamsport Regional Airport (USW00014778), 524 ft elevation, 19.0 miles from the population centre. Daily records from 1948 to October 26, 2026; 100.0% 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 USW00014778.
• 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.
• 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.