Norristown

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond this area.
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.

Every large fire

1. Large fires mapped by the Monitoring Trends in Burn Severity program since 1984: 1,000 acres or more in the West, 500 or more in the East. Prescribed burns are excluded. Acres here are the part of each perimeter inside this place.

Monitoring Trends in Burn Severity (USGS and U.S. Forest Service), 1984 to 2026.

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.

Flood insurance figures are for Montgomery County, the county that contains Norristown.

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 in Montgomery County, the county that contains Norristown.

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.

The drought index is for Montgomery County, the county that contains Norristown.

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 city centre.
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

Landslides mapped in Montgomery County.

Mapped by NASA (2).

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. Jun 16, 2001Flash Flood$33.5 million
   National Weather Service narrative

   The remnants of tropical storm Allison drenched the southern halves of Montgomery and Bucks Counties and Philadelphia with up to 10 inches of rain. Torrential downpours occurred from early afternoon through the late evening on the 16th. Severe flooding occurred along the Sandy Run, Wissahickon, Pennypack and Neshaminy Basins. The flooding caused and then hampered fire fighters battling an apartment fire in Upper Moreland Township. Six persons perished in the fire. A 63-year-old man died when his 1997 Toyota was swept into the Wissahickon Creek in Whitemarsh Township (Montgomery County). Several bridges were damaged or washed out including a couple on the SEPTA Regional Rail Lines.…

2. Jun 27, 2006Flood$22.0 million
   National Weather Service narrative

   Several days of heavy rain throughout the Schuylkill River Basin culminated with moderate flooding along the Schuylkill River and its tributaries from the 27th through the 29th. President George W. Bush declared Montgomery County a disaster area. Sporadic periods of heavy rain started on the 23rd, but the most widespread and heaviest rain fell from the night of the 27th into the morning of the 28th. Even heavier rain fell farther upstream in Berks and Schuylkill Counties. During bursts of heavier rain on the 28th, flash flooding of smaller streams occurred and the ongoing flooding along the main stem rivers was exacerbated. Event totals in Montgomery County averaged five to nine…

3. Sep 8, 1996Flash Flood$20.0 million
   National Weather Service narrative

   Thunderstorms, which "trained" or moved over the same locations of Southern Montgomery County, caused widespread flash flooding, caused the death of a couple in Abington and about $20 million dollars in property damage. Up to 10 inches of rain within a three hour period. The 10 inches of rain was measured at the water treatment plant off Fitzwatertown Road in Abington. This corresponded well with the Doppler Radar rainfall estimates of locations surrounding the severe flooding. Tropical moisture left behind by the remnants of Hurricane Fran was a major contributor to the torrential downpours. States of emergency were declared by several Montgomery County townships. Governor Ridge…

4. Sep 1, 2021Flash Flood$20.0 million
   National Weather Service narrative

   Widespread flash flooding occurred in Montgomery County with many road closures and vehicles stranded. Numerous water rescues took place. Many buildings and homes were flooded. Most waterways in the county overflowed their banks, including the Schuylkill River, Perkiomen Creek and Wissahickon Creek.

5. Sep 1, 2021Flash Flood$20.0 million
   National Weather Service narrative

   Widespread flash flooding occurred in Montgomery County with many road closures and vehicles stranded. Numerous water rescues took place. There were two flood related fatalities, one in Skippack and one in Bridgeport. Many buildings and homes were flooded. Most waterways in the county overflowed their banks, including the Schuylkill River, Perkiomen Creek and Wissahickon Creek.

6. Sep 1, 2021Flash Flood$20.0 million
   National Weather Service narrative

   Widespread flash flooding occurred in Montgomery County with many road closures and vehicles stranded. Numerous water rescues took place. Many buildings and homes were flooded. Most waterways in the county overflowed their banks, including the Schuylkill River, Perkiomen Creek and Wissahickon Creek.

7. Aug 2, 2009Flash Flood$12.0 million
   National Weather Service narrative

   Thunderstorms with torrential downpours caused flash flooding in several municipalities and a major mudslide across southern Montgomery County. Doppler Radar storm total estimates averaged between 2.5 inches and 4.5 inches.||In Lower Merion Township, a mudslide closed both directions of the Schuylkill Expressway at the Conshohocken Curve from 11 a.m. EDT through 230 p.m. EDT. The westbound lanes were reopened first and the eastbound lanes were reopened at 730 p.m. EDT. Motorists were stranded on the expressway when the mudslide initially occurred. Elsewhere in the township, the Mill Creek flooded and washed out a couple of roads in its basin. There were about a half dozen water…

8. Sep 16, 1999Flash Flood$12.0 million
   National Weather Service narrative

   Hurricane Floyd battered Eastern Pennsylvania (especially Southeast sections around Philadelphia) on September 16th and brought with it torrential and in some places record breaking rains and damaging winds. The hurricane caused widespread flash flooding as storm totals averaged around six inches in the Poconos and Berks County, eight inches in the Lehigh Valley and from eight to twelve inches in the Greater Philadelphia Metropolitan Area. Six people died directly from the hurricane - four drownings and two persons were hit by trees. The hurricane also indirectly contributed to the death of about seven other persons. About 40 persons were seriously injured. There were hundreds of…

9. Sep 18, 2003High Wind, Montgomery$7.0 million
   National Weather Service narrative

   Tropical Storm Isabel produced strong power outage producing winds, moderate tidal flooding along the Delaware River and stream flooding in Chester County. Isabel made landfall as a hurricane near Drum Inlet, North Carolina around 100 p.m. EDT on the 18th and weakened as it tracked farther inland. At one time in its life cycle, it was a powerful Category 5 hurricane when it was north of the Leewood Islands. Winds gusted up to 60 mph in Eastern Pennsylvania and downed countless numbers of trees, tree limbs and power lines. It was the worst outage on record for PECO Energy in southeastern Pennsylvania. About 572,425 of its customers lost power. This exceeded the outages that…

10. Sep 1, 2021Tornado$5.0 million
    National Weather Service narrative

    A semi-discrete supercell thunderstorm began to exhibit rotation |over Delaware County, PA around 5:15 PM on September 1. The |rotation continued north-northeast into Montgomery County, and |eventually strengthened enough to produce a tornado. Minor tree |damage was first observed along Stenton Ave in Fort Washington in |the area of the Philadelphia Cricket Club. A path of tree damage |was observed heading northeast along Joshua Rd and through Fort |Washington State Park. Some minor shingle and siding damage to |houses was also seen. ||Damage became more severe after the tornado crossed the |Pennsylvania Turnpike. At this time the tornado also moved into a |more residential area.…

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 3, 1966

All-time low

−7°F2 times, most recently Jan 22, 1984

Warmest night

83°F2 times, most recently Jul 23, 2011

Coldest day

6°FJan 19, 1994

Wettest day

8.02 inJul 28, 2013

Snowiest day

27.6 inJan 7, 1996

Hottest year

2012mean 58.9°F

Coldest year

1963mean 52.0°F

Wettest year

201164.33 in

Driest year

196529.34 in

Snowiest season

78.7 in2009-10

Station Phila International Airport (USW00013739), 7 ft elevation, 18.2 miles from the city centre. Daily records from 1940 to October 27, 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.

Declarations for Montgomery County.

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.

• 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 USW00013739.
• 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.