Hurricanes and Tornadoes That Hit Norristown, PA

The nearest NOAA station with 1991–2020 climate normals is Norristown, PA, 2 miles southeast of Norristown at 62 feet. July is the warmest, with an average high of 89°F and low of 67°F; January is the coolest, at 42°F and 23°F. August is the wettest at 5.0 inches of precipitation on average and February the driest at 3.0 inches; the year adds up to 50.7 inches over 86 days with at least a tenth of an inch. June to November, the hurricane season months, bring 53% of the year's precipitation (26.7 of 50.7 inches); the other six months are drier. September has brought the most of the 33 tropical systems that passed within 75 miles (15); a normal September there has highs of 80°F and 4.9 inches of precipitation. Highs reach 90°F on about 39 days a year, almost all from May to September. Lows fall below freezing on about 107 nights a year. Snowfall averages 25.3 inches a year, most of it in February. That 50.7 inches is more than at 133 of the 148 Pennsylvania stations used on this site (90%). Collegeville, 6 miles northwest, has its own station (Graterford 1 E, PA): 48.6 inches a year, 2.1 less than here, and a July average high of 86°F against 89°F.

Water temperature at the NOAA tide station Philadelphia, PA, 18 miles southeast, averaged 80°F in July and 38°F in February over 2021–2025. It averaged 80°F or warmer from July. Sea level at the Philadelphia tide gauge, 18 miles from Norristown, has risen 1.24 ± 0.04 inches per decade from 1900 to 2025, NOAA's linear trend; at that pace it is 12.4 inches in a hundred years. That is faster than at 73 of the 144 U.S. gauges with a NOAA trend.

Since 1996, the National Weather Service has logged 575 flood, rain, thunderstorm wind and lightning events that began within 10 miles of Norristown: 394 thunderstorm wind reports, 118 flash floods, 45 floods, 12 lightning strikes and 6 heavy rain events. They killed 5 people and injured 8, and the NWS estimated $55.3 million in property and crop damage. The strongest thunderstorm gust on record here was 81 mph, on October 31, 2019. August has had the most flash floods, 48 of 118. Of the 788 Pennsylvania cities on this site with a flash flood on record, 687 have had fewer than Norristown.

Flood insurance policyholders in Norristown's 2 ZIP codes have filed 999 claims with the National Flood Insurance Program since 1978, and were paid $25.0 million for buildings and contents, in the dollars of each year. The most came from Hurricane Ida in 2021: 98 claims (10% of all) and $10.2 million, then Hurricane Floyd in 1999 with 74 and Not a named storm in 1979 with 68. 48% of the claims carry the name of a storm or flood event; the rest have no event name. Of the 553 Pennsylvania cities on this site with 10 or more claims, 546 have fewer than Norristown.