U.S. Extremes

Record of -17 degrees F at Civilian Conservation Corps Logging Camp F-16 is congruent with similar low temperatures observed in the area on January 27, 1940. This observation is archived as part of the National Archives CCC collection.

The record minimum temperature of -50 degrees F was observed by an automated observing station operated by the US Geological Survey (USGS) at a river gage on the Big Black River near the Canadian border. The data are archived by the USGS, and the validity of the observation was confirmed by the State Climate Extremes Committee. The value also ties observations in NH and VT for the coldest temperature recorded for the Northeast region of the United States.

Value of -50 degrees F exceeds the previously reported all-time minimum temperature extreme of -46 on 1/8/1968. The -50 degrees F is not yet present in NCDC's digital data files but exists on observation forms and publications in NCDC archives. The value ties with Vermont and Maine for coldest temperature recorded in the Northeast region of the United States.

Previously reported record of -25 degrees F at Greene on February 5, 1996 could not be verified. Source is unknown and no documentation could be found. Value is exceeded by the currently reported record at Wood River Junction.

The previously reported record of -69 degrees F set at Peter's Sink on Feb 1, 1985 is widely considered an accurate observation, but no information concerning the observation or the station could be identified, and the value is heavily affected by the local terrain. The -50 degrees F at Strawberry Tunnel is the coldest temperature observation that can be verified from publicly available observations at established observation stations in Utah.

The -50 degrees F minimum temperature ties with values from NH and ME as the all-time coldest temperature for the Northeast region of the United States.

The date for the existing record of -30 degrees F at Mountain Lake Biological Station was incorrect by one day. Date listed is the correct observation date.

Original observation of -66 degrees F at Riverside Ranger Station on February 9, 1933 is maintained in Department of Interior archives.

A 118 degrees F temperature that had persisted in the record books at Bennett, CO on July 11, 1888 was found to be a typographical transcription error. Area temperatures were at least 15-20 degrees cooler that date (the highest being a 105 degrees F observation at Glenwood Springs).

The value of 118 degrees F is confirmed as a valid observation, but the station sits on a bluff above the river and the observation is characteristic more of the local microclimate than the area climate. If this value is in doubt, the next highest value is 117 degrees F on July 25, 1936 at both Logan and Atlantic.

The previously reported record of 114 degrees F was reported by observer at Moorhead on 7/6/1936 as 113.6 degrees F (unlikely to be accurate given the 1-degree precision of the mercury in glass thermometer in use at the time), and rounded to 114 degrees F. The extreme reported above for Beardsley was observed as 114.5 degrees F and has been rounded to 115 degrees F per current rounding practices.

Listed record value of 104 degrees F is being reviewed. If found to be invalid, the next highest temperature is 100 degrees F on August 21, 2003 at Ponce 4E.

A 118 degrees F temperature was observed on July 4, 2007 at a Remote Automated Weather Station (RAWS) located near the Utah Welcome Center on I-15 south of St. George. However, a decision on the validity of this value has not yet been reached by the State Climate Extremes Committee.

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.

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.

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.

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 acknolwedged record of 11.08" at Holly on June 17, 1965 was superseded.

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.

The 38.00 inches in 24-hrs at Kilauea Sugar Co. Plantation (Kauai) on January 24-25, 1956 is an estimate, but is listed as the record because it was obtained from a reliable rain gauge and is deemed conservative by an inch or more (that is, the 12-inch gauge was overflowing when it was emptied for the first time). Storm reports indicated 41.90 inches fell over period 9 AM 1/24/56 to 3 PM 1/25/56 (including 6-inches in 30 minutes and 12 inches in the first hour). The greatest accurately observed 24-hr precipitation is 31.95 inches at Honomu (Hawaii) on February 20, 1918. More information on the January 24-25, 1956 Kilauea storm rain fall can be found on page 10 of the Weather Bureau's 1961 "Climate of the States: Hawaii (Climatography of the United States No. 60-51)".

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.

The previously posted value of 13.53" was discovered to be in error. An investigation to determine the legitimate record is underway.

Historical value was examined retroactively and found to be valid and exceeded prior stated record.

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.

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.

Value was observed during the passage of Tropical Storm Isabel (October 4-8, 1985).

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.

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.

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.

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.

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.

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.

The 24-hr snowfall at Ansonia 1NE was the result of a powerful blizzard which impacted the Tri-State Region. After the storm subsided, many locations around the region reported more than 30 inches of snow. The State Climate Extremes Committee verified the validity of the observation at Ansonia.

State climatologist reports a greater 24-hr snow fall that spanned 2 observational days.

The 30.0 inches observed at Pratt in 2009 was formally evaluated by the State Climate Extremes Committee.

The 13.0 inches observed at Colfax on February 13, 1960 is the greatest 24-hr snowfall that could be confirmed for Louisiana. It is likely that higher 24-hr amounts fell during the Valentine's Day blizzard of February 13-15, 1895 (in which storm totals of 14 to 24 inches were prevalent from Galveston, TX to Lake Charles, LA) as well as the blizzard of December 21-22, 1929. However, all reported snow falls from these events appear to be accumulated amounts from which daily totals cannot be reliably extracted.

An unofficial, but widely accepted 24-hr snow fall observation of 54 inches was recorded at Barnes Corner (Tug Hill Plateau) in January, 1976.

In May 2016, the SCEC considered a reported 41-inch snowfall event observed in January 2016 at Mt. Mitchell (GHCN-D identifier USC00315923). The value was determined to be invalid, and the existing record of 36 inches set in March 1993 was thereby upheld.

The 24-hr snow fall at Woodward and Freedom fell in conjunction with a spring blizzard that set snow fall records in Oklahoma, Kansas and Texas. The State Climate Extremes Committee verified the validity of the observations at Woodward and Freedom.

A potential 24-hour snowfall record of 50.8 inches over a 24-hour period on 24-25 December 2017 at Erie International Airport was examined by the SCEC during the following year. The SCEC found that observational practices associated with the Erie total reduced confidence in the value. The SCEC determined by a 4-1 vote that the existing Morgantown record be upheld. View report

Historical value was examined retroactively and found to be valid and exceeded prior stated record. The previously recognized record of 25", observed in March 2009 at Follett (GHCN-D identifier USC00413225) is documented (here).

55.5 inches of snow fall in 24 hours was reported at the Alta Guard Station in Alta, UT on January 5-6, 1991, but information concerning this observation or the station is unavailable and cannot be considered official.

The observation of 65.0 inches of snow that fell in 24 hours at the Crystal Mountain ski resort on February 24, 1994 is archived at the Northwest Weather and Avalanche Center. The greatest 24-hr snow fall observed at an official NOAA weather station in Washington is 52.0 inches observed at Winthrop on January 21, 1935.

The 35.0 inches of snowfall reported at Flat Top fell from 10 AM on January 27th to 10 AM on January 28th, 1998. Observation-time values for each day are 30.0 and 8.0 inches, respectively.

236 inches of snow depth were observed at the Collins snow study observation site at Alta, UT on May 19, 1983, but information concerning this observation or the station is unavailable and cannot be considered official.