Alabama |
32 |
813 |
(Dauphin Island Sea Lab) |
Although higher amounts have been observed in other states, the 32.52 inches of rainfall that was observed in 24-hrs over July 19-20, 1997 at Dauphin Island Sea Lab in conjunction with Hurricane Danny is the greatest 24-hr rainfall that has been directly observed at an officially established observation station within the coterminous United States.
|
Alaska |
15 |
381 |
(Seward) |
The previously-listed state record of 15.2 inches at Angoon on October 12, 1982 was determined to be invalid by the SCEC, based largely on analysis that resulted in this Bulletin of the American Meteorological Society article.
|
Arizona |
11 |
279 |
(Workman Creek) |
|
Arkansas |
14 |
356 |
(Big Fork) |
|
California |
25 |
635 |
(Hoegees Camp) |
Hourly precipitation values for Hoegee's Campground (in the mountains outside Los Angeles) indicate the greatest 24-hour rainfall occurred between 1:00 AM on January 22nd to 1:00 AM on January 23rd. During that period, the storm delivered 25.83 inches (corrected from previous reports of 26.12 inches). A detailed post-storm report was produced by the Weather Bureau.
|
Colorado |
11 |
279 |
(Usgs Rod & Gun (ft. Carson)) |
Had a 9 AM to 9 AM observing period been used ending at 9 AM on September 13th, that the measurement would have been 12.46\". However, the SCEC chose to confirm the calendar-day value as the official record. In either case, the previously acknowledged record of 11.08\" at Holly on June 17, 1965 was superseded.
|
Connecticut |
12 |
305 |
(Burlington) |
|
Delaware |
12 |
305 |
(Harbeson) |
The Harbeson value replaced the previously reported record of 8.5 inches, set at Dover on 13 July 1975. However, the SCEC reviewing the Harbeson record determined that the Dover record had actually been exceeded twice between 1975 and the Harbeson event, during Tropical Storms Floyd (1999) and Irene (2011). More details are available in the report associated with this investigation.
|
Florida |
23 |
584 |
(Key West) |
The previously reported extreme of 38.70 inches at Yankeetown on September 5, 1950 is an estimated depth of rainfall calculated as part of a post-storm survey of Hurricane Easy (Cedar Keys Hurricane). Value has historically been considered reasonably accurate (and even an underestimate of actual rain fall), but as an estimate cannot be considered an official observation from a reliable precipitation gauge.
|
Georgia |
21 |
533 |
(Americus) |
|
Hawaii |
49 |
1245 |
(Waipā Garden (kauai)) |
This value exceeded the previous record of 38 inches, observed at Kilauea Sugar Co. Plantation on 24-25 January 1956, which itself was an estimate. The 2018 value also became the national record for 24-hour precipitation. View the associated National Climate Extremes Committee report. The members of the SCEC deferred to the NCEC findings.
|
Idaho |
7 |
178 |
(Rattlesnake Creek) |
|
Illinois |
16 |
406 |
(Aurora) |
|
Indiana |
10 |
254 |
(Princeton) |
|
Iowa |
13 |
330 |
(Atlantic 1ne) |
Previously reported record of 16.70 inches in Decatur Co. on August 5-6, 1959 is likely valid, but was estimated from a post-event survey observation. A 13.52 inch observation was made at Atlantic 5SW on June 14, 1998, but it is likely that the observation covered more than a 24-hr period.
|
Kansas |
0 |
0 |
(Under Review) |
The previously posted value of 13.53\" was discovered to be in error. An investigation to determine the legitimate record is underway.
|
Kentucky |
11 |
279 |
(Mayfield 6sw) |
The previous record of 10.48 inches set back on March 1, 1997 in Louisville was determined to be a calendar-day record rather than a 24-hour record. The 24-hour record should have been 10.50 inches from 1AM CST March 1 to 1AM CST March 2, 1997 from the same event in Louisville. This new record value of 11.28 inches from Mayfield exceeds both values.
|
Louisiana |
22 |
559 |
(Hackberry) |
|
Maine |
13 |
330 |
(Portland) |
|
Maryland |
14 |
356 |
(Jewell (nr. Friendship)) |
|
Massachusetts |
18 |
457 |
(Westfield) |
|
Michigan |
12 |
305 |
(6e Fountain) |
The 2019 value replaced the previous record of 9.78 inches, set at Bloomingdale on 31 August 1914. View the report associated with this investigation.
|
Minnesota |
15 |
381 |
(Hokah 1s) |
|
Mississippi |
15 |
381 |
(Columbus) |
|
Missouri |
18 |
457 |
(Edgerton) |
|
Montana |
11 |
279 |
(Circle (springbrook)) |
|
Nebraska |
13 |
330 |
(York) |
|
Nevada |
7 |
178 |
(Mount Charleston) |
|
New Hampshire |
11 |
279 |
(Mount Washington) |
|
New Jersey |
14 |
356 |
(Tuckerton) |
|
New Mexico |
11 |
279 |
(Lake Maloya) |
|
New York |
13 |
330 |
(Long Island Macarthur Airport) |
|
North Carolina |
22 |
559 |
(Altapass) |
|
North Dakota |
8 |
203 |
(Litchville) |
|
Ohio |
10 |
254 |
(Lockington Dam (nr. Sidney, Shelby Co. Oh)) |
Value is published in the August 1995 Storm Data publication and is from a reliable gauge. Higher 24-hr amounts may have occurred in conjunction with a line of severe storms that impacted Northwest Ohio on July 4-5, 1969.
|
Oklahoma |
15 |
381 |
(Enid) |
|
Oregon |
11 |
279 |
(Nehalem 9ne) |
|
Pennsylvania |
13 |
330 |
(York 3ssw Pump Stn) |
Arguably the greatest 24-hour rainfall on record outside of the tropics occurred around Smethport, PA on July 17, 1942. A post-event survey by the Weather Bureau provided a widely accepted maximum storm rainfall of 34.50 inches within a 12 hour period, of which an estimated 30.60 inches fell in just 6 hours. However, the greatest observed 24-hr rain fall for Pennsylvania occurred in conjunction with Hurricane Agnes in 1972.
|
Puerto Rico |
23 |
584 |
(Toro Negro Forest) |
Value was observed during the passage of Tropical Storm Isabel (October 4-8, 1985).
|
Rhode Island |
12 |
305 |
(Westerly) |
|
South Carolina |
14 |
356 |
(Myrtle Beach) |
Previously listed record of 17.00 inches at Antreville on Augst 27, 1995 (Tropical Storm Jerry) was incongruent with other observations in the area, and all reliable evidence pointed to a much smaller 24-hr value. The 14.80 inches observed at Myrtle Beach on September 16, 1999 is a result of Hurricane Floyd.
|
South Dakota |
8 |
203 |
(Groton) |
The reported value was evaluated by the State Climate Extremes Committee. Greater amounts have fallen in 24 hours or less across SD, but were not observed by reliable precipitation measurement gauges. A survey after the June 9, 1972 Black Hills flood indicated rainfall up to 15 inches in 6 hours may have occurred near Keystone. On June 13-14, 1976 up to 10 inches of rain may have fallen over the Black Hills, while on June 14, 1996 a near-stationary thunderstorm produced an estimated 14 inches of rain between Sturgis and Hereford. On August 17, 2007 an estimated 10.5 inches of rain fell west of Hermosa. Slow moving thunderstorms on May 8, 2018 produced large storm totals across parts of SD including an unofficial 24-hour report measuring 13.15 inches northwest of Long Lake.
|
Tennessee |
20 |
508 |
(Mcewen) |
The 2021 value replaced the previous record of 13.60 inches, set at Milan (COOP ID: 406012) on 13 September 1982.
|
Texas |
42 |
1067 |
(Alvin) |
The 24-hour rainfall of 42.00 inches was reported from an observer 8.5 miles west of Alvin, Texas between 7 AM July 25th and 7 AM July 26th, 1979 in conjunction with Tropical Storm Claudette. Observer reported that the 10-inch gauge was overflowing at his 1 AM reading, and so the 42 inches may be underreported by at least 3 inches. This 42.00-in rainfall exceeds any observed 24-hr precipitation value for the United States. 43.00 inches of rain in this storm is acknowledged as the United States national record 24-hr precipitation amount, but that value appears to have been estimated in a post-storm survey and is therefore not listed here.
|
Utah |
5 |
127 |
(Deer Creek Dam) |
A value of 8.40 inches was reported as part of a post-flash flood survey conducted by the National Weather Service at North Odgen on September 7-8, 1991.
|
Vermont |
9 |
229 |
(Mt. Mansfield) |
|
Virgin Islands (U.S.) |
20 |
508 |
(Anna's Hope (sc)) |
|
Virginia |
14 |
356 |
(Williamsburg 2n) |
Storm Data (Vol. 11, No. 8) reports associated with Hurricane Camille (August 1969) indicate \"... substantiated amounts up to 31 inches ... falling mainly in Nelson and adjacent counties ....\" The 14.28 inches at Williamsburg fell in conjunction with Hurricane Floyd.
|
Washington |
14 |
356 |
(Mt. Mitchell #2) |
|
West Virginia |
12 |
305 |
(Brushy Run) |
It is widely accepted that the greatest precipitation in a 24 hr period for West Virginia was an estimated 19.00 inches that reportedly fell in 2 hrs and 10 minutes on July 18, 1889 at Rockport during a cloudburst that caused Tygart Creek to rise 22 feet in one hour. However, this value has not been confirmed.
|
Wisconsin |
11 |
279 |
(Mellen) |
|
Wyoming |
6 |
152 |
(Cheyenne) |
|