Pennsylvania, 1999

Heavy Rain in Pennsylvania, September 9, 1999

September 9, 1999 · NWS PHI · 4 events in 4 counties and zones

Thunderstorms with heavy rain produced poor drainage and minor street flooding across Philadelphia and the nearby suburbs during the late evening of September 9th. Rainfall rates were as heavy as 2 inches per hour, but the thunderstorms moved fast enough to prevent creeks and streams from flooding.

Where it happened

Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

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The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
4

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS PHI wrote it up.

Thunderstorms with heavy rain produced poor drainage and minor street flooding across Philadelphia and the nearby suburbs during the late evening of September 9th. Rainfall rates were as heavy as 2 inches per hour, but the thunderstorms moved fast enough to prevent creeks and streams from flooding. Heavy rain fell throughout the city of Philadelphia, but affected mainly eastern Chester County, Lower Montgomery County and central Bucks County in the surrounding suburbs. Storm totals included 2.48 inches in Doylestown (Bucks County), 2.18 inches in King of Prussia (Montgomery County), 1.77 inches at the Philadelphia International Airport, 1.73 inches in Valley Forge (Chester County) and 1.70 inches at the Willow Grove NAS.

The radar

The national radar mosaic for the moment the first event began.

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Event by event

4 heavy rain. Local standard time, as filed.

Heavy Rain, Bucks

When
September 9, 8:00 PM EST to 10:00 PM EST
Where
Bucks County, Doylestown
Reported by
AWOS,ASOS,MESONET,ETC
Coordinates
40.337, -75.107 (the zone’s center; the record gives no point)

Heavy Rain, Montgomery

When
September 9, 8:00 PM EST to 10:00 PM EST
Where
Montgomery County, King of Prussia
Reported by
TRAINED SPOTTER
Coordinates
40.211, -75.367 (the zone’s center; the record gives no point)

Heavy Rain, Chester

When
September 9, 8:00 PM EST to 10:00 PM EST
Where
Chester County, Valley Forge
Reported by
AWOS,ASOS,MESONET,ETC
Coordinates
39.973, -75.748 (the zone’s center; the record gives no point)

Heavy Rain, Philadelphia

When
September 9, 9:00 PM EST to 11:00 PM EST
Where
Philadelphia County, Countywide
Reported by
AWOS,ASOS,MESONET,ETC
Coordinates
40.008, -75.134 (the zone’s center; the record gives no point)

What these are

Heavy Rain
Rainfall totals unusual for the place and season that did not produce a flood.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Pennsylvania in 1999Every state in 1999This day in weather historyWarnings in Pennsylvania, September 1999

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-10-01. Each event’s entry at NCEI: 5722361, 5722362, 5722364, 5722363.