Flooding and Hail in Arizona, September 1 to 20, 1999

Name: Flooding and Hail in Arizona, September 1 to 20, 1999
Start: 1999-09-01T20:00
End: 1999-09-20T16:20
Location: Arizona

September 1 to 20, 1999 · NWS PSR · 21 events in 5 counties and zones

9 thunderstorm wind, 8 hail, 2 flood, 1 heavy rain, 1 lightning, as filed by the National Weather Service.

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: 5
Property damage: $37 million
Crop damage: $50,000
Events: 21

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.

The radar

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

Open the radar archive at this moment

Event by event

9 thunderstorm wind, 8 hail, 2 flood, 1 heavy rain, 1 lightning. Local standard time, as filed.

Flood, Maricopa

When: September 1, 8:00 PM MST to 9:00 PM MST
Where: Maricopa County, Mesa
Reported by: TRAINED SPOTTER
Coordinates: 33.349, -112.491 (the zone’s center; the record gives no point)

Heavy Rain, Maricopa

When: September 11, 7:00 PM MST to 9:00 PM MST
Where: Maricopa County, 10 mi N of Sun City
Reported by: TRAINED SPOTTER
Coordinates: 33.349, -112.491 (the zone’s center; the record gives no point)

About 2 inches of rain fell in about 2 hours.

Thunderstorm Wind, Maricopa

When: September 14, 4:55 PM MST to 5:15 PM MST
Where: Maricopa County, Chandler to Mesa
Measured: 75 kt (86 mph)
Injuries: 2 direct, 0 indirect
Property damage: $5.0 million
Reported by: EMERGENCY MANAGER
Coordinates: 33.300, -111.830

Winds blew down power poles, trees, and caused considerable damage to homes and businesses in the East Valley. A family in Mesa was trapped inside their vehicle for about an hour after power poles crashed down around them. Power outages affected at least 8,500 customers in the East Valley. The Mesa Regal RV Resort suffered major damage as three trailers were totally destroyed. An airplane was flipped over at Falcon Field with damage to hangar doors. Sky Harbor airport reported numerous flight delays.

Hail, Maricopa

When: September 14, 5:09 PM MST to 5:15 PM MST
Where: Maricopa County, Mesa
Measured: 1.5 in hail
Reported by: TRAINED SPOTTER
Coordinates: 33.420, -111.820

Large hail reported from several spotters in East Mesa.

Hail, Maricopa

When: September 14, 5:35 PM MST
Where: Maricopa County, Phoenix
Measured: 1.5 in hail
Reported by: OFFICIAL NWS OBS.
Coordinates: 33.480, -112.070

A series of thunderstorms developed quickly and moved northeast through the east side of the city.

Thunderstorm Wind, Maricopa

When: September 14, 5:35 PM MST
Where: Maricopa County, 15 mi NW of Phoenix
Measured: 65 kt (75 mph)
Property damage: $2.0 million
Reported by: EMERGENCY MANAGER
Coordinates: 33.630, -112.250

Considerable damaage in NW Phoenix and Peoria due primarily to strong wind.

Lightning, Maricopa

When: September 14, 8:00 PM MST
Where: Maricopa County, Mesa
Injuries: 1 direct, 0 indirect
Reported by: EMERGENCY MANAGER
Coordinates: 33.349, -112.491 (the zone’s center; the record gives no point)

A 32-year old woman was knocked unconscious as lightning struck a nearby tree.

Thunderstorm Wind, Pinal

When: September 14, 8:15 PM MST
Where: Pinal County, 5 mi W of Casa Grande
Measured: 70 kt (81 mph)
Reported by: NEWSPAPER
Coordinates: 32.880, -111.830

Winds destroyed at least one mobile home and damaged others in the Casa Grande West subdivision.

Hail, Pinal

When: September 15, 4:45 PM MST
Where: Pinal County, Apache Jct
Measured: 1 in hail
Reported by: TRAINED SPOTTER
Coordinates: 33.420, -111.550

Hail, Pinal

When: September 15, 4:46 PM MST
Where: Pinal County, Coolidge
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 32.970, -111.520

Hail, Pinal

When: September 15, 5:30 PM MST
Where: Pinal County, 3 mi W of Superior
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 33.280, -111.150

Large hail was reported throughout the area along with heavy rain. One spotter about 7 miles east of Superior, at Top of the World, reported 1.10 inch in just 25 minutes.

Hail, La Paz

When: September 16, 4:12 PM MST
Where: La Paz County, 12 mi S of Parker
Measured: 1 in hail
Reported by: LAW ENFORCEMENT
Coordinates: 33.980, -114.280

Hail, La Paz

When: September 16, 6:33 PM MST
Where: La Paz County, Vicksburg
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 33.750, -113.750

Flood, Gila

When: September 16, 10:30 PM MST to 11:05 PM MST
Where: Gila County, Roosevelt
Reported by: TRAINED SPOTTER
Coordinates: 33.800, -110.812 (the zone’s center; the record gives no point)

About 2 inches of rain fell in about 15 minutes and resulted in street flooding.

Thunderstorm Wind, Maricopa

When: September 19, 1:15 PM MST to 1:28 PM MST
Where: Maricopa County, Scottsdale
Measured: 70 kt (81 mph)
Property damage: $100,000
Reported by: NEWSPAPER
Coordinates: 33.480, -111.900

Major roof damage at a strip mall on East Indian School Road.

Hail, Pinal

When: September 19, 1:31 PM MST to 1:45 PM MST
Where: Pinal County, 10 mi NW of Coolidge
Measured: 1.25 in hail
Property damage: $100,000
Crop damage: $50,000
Reported by: TRAINED SPOTTER
Coordinates: 33.070, -111.630

Hail and strong winds ripped through the Coolidge area and damaged thousands of acres of cotton just weeks before it would have been harvested.. Trees were uprooted in Coolidge, and power poles were down in Coolidge and Florence. Heavy rain was also recorded at the Casa Grande Ruins National Monument where 2.02 inches fell in about 45 minutes. About 41 homes in Blackwater, on the Gila River Indian Community, had either roof damage, broken windows, or door and skirting damages.

Thunderstorm Wind, Pinal

When: September 19, 1:35 PM MST to 1:40 PM MST
Where: Pinal County, Florence
Measured: 60 kt (69 mph)
Property damage: $30,000
Reported by: LAW ENFORCEMENT
Coordinates: 33.030, -111.380

Windows blown out of the guard towers, and roof torn off at the nearby prison. Nearby Sacaton, on the Gila River Indian Community, had 13 homes damaged by the storm. Minor and major roof damages, coolers damaged, windows broken, carport damage, trailer sidings and trailer damages.

Thunderstorm Wind, Maricopa

When: September 19, 2:00 PM MST to 4:00 PM MST
Where: Maricopa County, Laveen
Measured: 80 kt (92 mph)
Property damage: $165,000
Reported by: LAW ENFORCEMENT
Coordinates: 33.370, -112.170

Four homes were reported damaged, with ceiling leaks, damaged windows, minor and major roof damage, and one home partially habitable.

Thunderstorm Wind, Maricopa

When: September 19, 3:15 PM MST
Where: Maricopa County, Mesa
Measured: 90 kt (104 mph)
Injuries: 2 direct, 0 indirect
Property damage: $30 million
Reported by: NEWSPAPER
Coordinates: 33.420, -111.820

Microburst winds struck the Desert Sands Trailer Park where at least 14 homes were totally destroyed and about 340 homes were damaged. Over 200,000 customers lost power after more than 40 power poles were snapped by the winds and rain. Talley Industries, on Greenfield Road received about $500,000 in damage as a large portion of the roof was removed by wind. A large truck was overturned near 80th Street and Baseline Road. Trees were uprooted in nearby Gilbert.

Thunderstorm Wind, Maricopa

When: September 19, 10:00 PM MST to 10:20 PM MST
Where: Maricopa County, Sun City
Measured: 70 kt (81 mph)
Reported by: EMERGENCY MANAGER
Coordinates: 33.600, -112.280

Winds gusted to 81 mph along with 1.9 inches of rain in Sun City West. Portions of two roofs were removed and dozens of trees were blown over at the Grandview Golf Course.

Thunderstorm Wind, Yuma

When: September 20, 4:20 PM MST
Where: Yuma County, Wellton
Measured: 60 kt (69 mph)
Reported by: TRAINED SPOTTER
Coordinates: 32.670, -114.130

Power poles down.

What these are

Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.
Heavy Rain: Rainfall totals unusual for the place and season that did not produce a flood.
Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Lightning: A lightning strike that killed, injured or caused damage.

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

The same day elsewhere

Every storm in Arizona in 1999 Every state in 1999 This day in weather history Warnings in Arizona, 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 2026-09-24. Each event’s entry at NCEI: 5718052, 5718053, 5718148, 5718149, 5718146, 5718150, 5718151, 5718147, 5718156, 5718157, 5718158, 5718265, 5718266, 5718267, 5718154, 5718153, 5718152, 5718269, 5718270, 5718155, 5718268.