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Data as of 2025-12-31
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Built 2026-10-17 (17 October 2026)

Herrs Island Dam Weather Records (USC00363831)

Record envelope, standing records and threshold days for Herrs Island Dam (USC00363831), Pennsylvania, United States, with 40 years of record.

Key Facts for Herrs Island Dam

  • Herrs Island Dam (USC00363831) is a weather station in Pennsylvania, United States at 40.45 latitude and -79.98 longitude, 220 m (720 ft) above sea level.
  • The station reports from 1898 to 1937, 40 years of record.
  • 0 records set at Herrs Island Dam still stand.
  • Records are tracked for prcp: an element needs 30 years of data to be eligible.
  • Herrs Island Dam set a daily record precipitation of 19.3 mm (0.8 in) on 18 December 1937.

About the Station

  • Location: Pennsylvania, United States, 40.45 latitude, -79.98 longitude.
  • Elevation: 220 m (720 ft).
  • Period of record: 1898 to 1937, 40 years.
  • Eligible elements: prcp.

Daily Record Envelope and 2026

0 days at or beyond a record
Daily record high and record low at Herrs Island Dam, with 2026 drawn through them The band shows the record high and record low for each calendar day at Herrs Island Dam. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius. 000111 JanFebMarAprMayJunJulAugSepOctNovDec
The band shows the record high and record low for each calendar day at Herrs Island Dam. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.
Daily record high and record low at Herrs Island Dam, with 2026 drawn through them
MonthHighest record highLowest record low2026 highest maximum2026 lowest minimum
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Which Years Hold Standing Records

0 standing records
Standing records at Herrs Island Dam by the year they were set 0 records at Herrs Island Dam still stand. 00000000000
0 records at Herrs Island Dam still stand.
Standing records at Herrs Island Dam by the year they were set
Year setStanding records

Wettest Day of Each Month

Jun: 89.2 mm (3.5 in)
Record daily precipitation for each month at Herrs Island Dam The wettest day on record for each calendar month at Herrs Island Dam. The most was 89.2 mm (3.5 in) on 26 June 1921. 0255075100 Jan: 38.9 mm (1.5 in), 22 January 1917 Jan Feb: 61.0 mm (2.4 in), 25 February 1930 Feb Mar: 48.0 mm (1.9 in), 17 March 1936 Mar Apr: 57.2 mm (2.3 in), 15 April 1922 Apr May: 47.8 mm (1.9 in), 25 May 1933 May Jun: 89.2 mm (3.5 in), 26 June 1921 Jun Jul: 71.1 mm (2.8 in), 22 July 1927 Jul Aug: 51.3 mm (2.0 in), 12 August 1914 Aug Sep: 58.4 mm (2.3 in), 20 September 1906 Sep Oct: 71.6 mm (2.8 in), 10 October 1936 Oct Nov: 54.6 mm (2.1 in), 16 November 1926 Nov Dec: 50.8 mm (2.0 in), 15 December 1901 Dec
The wettest day on record for each calendar month at Herrs Island Dam. The most was 89.2 mm (3.5 in) on 26 June 1921.
Record daily precipitation for each month at Herrs Island Dam
MonthRecord daily precipitation (mm)Date
Jan38.9 mm (1.5 in)22 January 1917
Feb61.0 mm (2.4 in)25 February 1930
Mar48.0 mm (1.9 in)17 March 1936
Apr57.2 mm (2.3 in)15 April 1922
May47.8 mm (1.9 in)25 May 1933
Jun89.2 mm (3.5 in)26 June 1921
Jul71.1 mm (2.8 in)22 July 1927
Aug51.3 mm (2.0 in)12 August 1914
Sep58.4 mm (2.3 in)20 September 1906
Oct71.6 mm (2.8 in)10 October 1936
Nov54.6 mm (2.1 in)16 November 1926
Dec50.8 mm (2.0 in)15 December 1901

Latest Records

20
Latest records at Herrs Island Dam
DateStationRecordValueBeat old record byOld record stoodSignificance
18 December 1937Herrs Island Dam, USdaily rain19.3 mm (0.8 in)1.5 mm (0.06 in)22 years12 of 100 (Routine)
12 November 1937Herrs Island Dam, USdaily rain15.2 mm (0.6 in)1.2 mm (0.05 in)16 years9 of 100 (Routine)
28 October 1937Herrs Island Dam, USdaily rain15.0 mm (0.6 in)2.3 mm (0.09 in)18 years11 of 100 (Routine)
7 August 1937Herrs Island Dam, USdaily rain34.3 mm (1.4 in)17.5 mm (0.7 in)2 years22 of 100 (Routine)
6 May 1937Herrs Island Dam, USdaily rain14.5 mm (0.6 in)1.0 mm (0.04 in)7 years7 of 100 (Routine)
5 May 1937Herrs Island Dam, USdaily rain19.3 mm (0.8 in)4.1 mm (0.16 in)23 years15 of 100 (Routine)
27 April 1937Herrs Island Dam, USdaily rain19.6 mm (0.8 in)4.4 mm (0.17 in)24 years17 of 100 (Routine)
26 April 1937Herrs Island Dam, USdaily rain52.1 mm (2.1 in)31.3 mm (1.2 in)23 years50 of 100 (Notable)
25 January 1937Herrs Island Dam, USdaily rain32.3 mm (1.3 in)13.8 mm (0.5 in)8 years29 of 100 (Routine)
21 January 1937Herrs Island Dam, USdaily rain29.2 mm (1.1 in)7.6 mm (0.30 in)33 years25 of 100 (Routine)
18 January 1937Herrs Island Dam, USdaily rain23.6 mm (0.9 in)8.9 mm (0.35 in)27 years20 of 100 (Routine)
15 January 1937Herrs Island Dam, USdaily rain28.7 mm (1.1 in)12.4 mm (0.5 in)19 years29 of 100 (Routine)
10 January 1937Herrs Island Dam, USdaily rain10.2 mm (0.4 in)1.1 mm (0.04 in)36 years15 of 100 (Routine)
20 December 1936Herrs Island Dam, USdaily rain22.6 mm (0.9 in)4.8 mm (0.19 in)33 years19 of 100 (Routine)
2 December 1936Herrs Island Dam, USdaily rain13.7 mm (0.5 in)1.5 mm (0.06 in)16 years9 of 100 (Routine)
5 November 1936Herrs Island Dam, USdaily rain30.5 mm (1.2 in)13.5 mm (0.5 in)33 years30 of 100 (Routine)
4 November 1936Herrs Island Dam, USdaily rain23.9 mm (0.9 in)12.5 mm (0.5 in)2 years19 of 100 (Routine)
26 October 1936Herrs Island Dam, USdaily rain16.3 mm (0.6 in)0.8 mm (0.03 in)18 years9 of 100 (Routine)
10 October 1936Herrs Island Dam, USmonthly rain71.6 mm (2.8 in)17.5 mm (0.7 in)7 years37 of 100 (Notable)
24 July 1936Herrs Island Dam, USdaily rain38.4 mm (1.5 in)22.4 mm (0.9 in)24 years32 of 100 (Routine)

Extremes by Year

1898 to 1937
Yearly extremes at Herrs Island Dam: the record and the median year
MeasureRecordYear of the recordMedian yearYears with a value
Wettest day (Rx1day)89.2 mm (3.5 in)192147.0 mm (1.9 in)40
Wettest five days (Rx5day)153.5 mm (6.0 in)192176.2 mm (3.0 in)40
Longest dry spell (CDD)32 days192316 days40

Wettest day (Rx1day)

Wettest day (Rx1day) at Herrs Island Dam by year The wettest day of the year at Herrs Island Dam, 1898 to 1937. The record is 89.2 mm (3.5 in) in 1921, marked on the chart; the median year is 47.0 mm (1.9 in). 204060801001900191019201930Record: 89.2 mm (3.5 in) in 1921
The wettest day of the year at Herrs Island Dam, 1898 to 1937. The record is 89.2 mm (3.5 in) in 1921, marked on the chart; the median year is 47.0 mm (1.9 in).
Wettest day (Rx1day) at Herrs Island Dam by year
YearWettest day (Rx1day)
189841.1 mm (1.6 in)
189945.7 mm (1.8 in)
190034.3 mm (1.4 in)
190153.1 mm (2.1 in)
190227.4 mm (1.1 in)
190347.8 mm (1.9 in)
190437.3 mm (1.5 in)
190550.8 mm (2.0 in)
190658.4 mm (2.3 in)
190737.6 mm (1.5 in)
190832.8 mm (1.3 in)
190937.3 mm (1.5 in)
191038.6 mm (1.5 in)
191158.4 mm (2.3 in)
191246.2 mm (1.8 in)
191345.0 mm (1.8 in)
191451.3 mm (2.0 in)
191529.5 mm (1.2 in)
191649.8 mm (2.0 in)
191738.9 mm (1.5 in)
191838.4 mm (1.5 in)
191938.1 mm (1.5 in)
192056.4 mm (2.2 in)
192189.2 mm (3.5 in)
192257.2 mm (2.3 in)
192361.0 mm (2.4 in)
192468.8 mm (2.7 in)
192534.5 mm (1.4 in)
192655.9 mm (2.2 in)
192771.1 mm (2.8 in)
192847.8 mm (1.9 in)
192954.1 mm (2.1 in)
193061.0 mm (2.4 in)
193141.4 mm (1.6 in)
193227.2 mm (1.1 in)
193347.8 mm (1.9 in)
193436.3 mm (1.4 in)
193545.0 mm (1.8 in)
193671.6 mm (2.8 in)
193752.1 mm (2.1 in)

Wettest five days (Rx5day)

Wettest five days (Rx5day) at Herrs Island Dam by year The wettest five days of the year at Herrs Island Dam, 1898 to 1937. The record is 153.5 mm (6.0 in) in 1921, marked on the chart; the median year is 76.2 mm (3.0 in). 0501001502001900191019201930Record: 153.5 mm (6.0 in) in 1921
The wettest five days of the year at Herrs Island Dam, 1898 to 1937. The record is 153.5 mm (6.0 in) in 1921, marked on the chart; the median year is 76.2 mm (3.0 in).
Wettest five days (Rx5day) at Herrs Island Dam by year
YearWettest five days (Rx5day)
189872.1 mm (2.8 in)
189957.9 mm (2.3 in)
190066.3 mm (2.6 in)
190194.6 mm (3.7 in)
190259.0 mm (2.3 in)
190374.7 mm (2.9 in)
190484.2 mm (3.3 in)
190582.2 mm (3.2 in)
190664.0 mm (2.5 in)
190773.1 mm (2.9 in)
190849.6 mm (2.0 in)
190971.9 mm (2.8 in)
191064.0 mm (2.5 in)
191178.7 mm (3.1 in)
1912107.9 mm (4.2 in)
191393.6 mm (3.7 in)
191475.9 mm (3.0 in)
191573.2 mm (2.9 in)
1916116.6 mm (4.6 in)
191747.9 mm (1.9 in)
191855.1 mm (2.2 in)
191975.0 mm (3.0 in)
192076.7 mm (3.0 in)
1921153.5 mm (6.0 in)
192287.9 mm (3.5 in)
192387.7 mm (3.5 in)
192476.5 mm (3.0 in)
192543.9 mm (1.7 in)
192695.9 mm (3.8 in)
192768.8 mm (2.7 in)
192875.0 mm (3.0 in)
192989.9 mm (3.5 in)
193082.6 mm (3.3 in)
193183.8 mm (3.3 in)
193269.2 mm (2.7 in)
193382.6 mm (3.3 in)
193480.3 mm (3.2 in)
193565.8 mm (2.6 in)
193684.2 mm (3.3 in)
1937106.8 mm (4.2 in)

Longest dry spell (CDD)

Longest dry spell (CDD) at Herrs Island Dam by year The longest dry spell of the year at Herrs Island Dam, 1898 to 1937. The record is 32 days in 1923, marked on the chart; the median year is 16 days. 102030401900191019201930Record: 32 days in 1923
The longest dry spell of the year at Herrs Island Dam, 1898 to 1937. The record is 32 days in 1923, marked on the chart; the median year is 16 days.
Longest dry spell (CDD) at Herrs Island Dam by year
YearLongest dry spell (CDD)
189815 days
189910 days
190015 days
190121 days
190215 days
190318 days
190424 days
190512 days
190612 days
190710 days
190821 days
190918 days
191014 days
191129 days
191223 days
191319 days
191416 days
191512 days
191618 days
191721 days
191820 days
191911 days
192024 days
192112 days
192225 days
192332 days
192423 days
192514 days
192615 days
192714 days
192813 days
192914 days
193015 days
193117 days
193216 days
193314 days
193425 days
193512 days
193626 days
193713 days

Each chart shows one value per year; the dot marks the record year. TXx is the hottest daily maximum, TNn the coldest daily minimum, Rx1day and Rx5day the largest one-day and five-day rain totals, and CDD the longest run of days with less than 1 mm of rain. A year with missing days can understate an extreme.

Rainfall Return Levels

37 years, 1899 to 1937

A day with at least 45.9 mm (1.8 in) of rain is expected about once in 2 years. A day with at least 85.9 mm (3.4 in) of rain is expected about once in 100 years.

Rainfall return levels at Herrs Island Dam: the daily rain expected about once in a given number of years
Expected about once inA day with at leastNote
2 years45.9 mm (1.8 in)
5 years57.8 mm (2.3 in)
10 years65.2 mm (2.6 in)
25 years74.0 mm (2.9 in)
50 years80.1 mm (3.2 in)Longer than the 37 years of record
100 years85.9 mm (3.4 in)Longer than the 37 years of record

The levels come from a generalised extreme value (GEV) distribution fitted by L-moments to the wettest-day total of each year, 37 years of values from 1899 to 1937.

A return level is an estimate. It is least reliable for the long periods, 50 and 100 years, and for any period longer than the record behind the fit, where the fit has to reach past the largest day actually observed. It is not a forecast.

The largest wettest-day totals in the fit: 89.2 mm (3.5 in) in 1921; 71.6 mm (2.8 in) in 1936; 68.8 mm (2.7 in) in 1924.

Download the Data

  • Data for Herrs Island Dam standing records by year: CSV or JSON. Field meanings are on the data page.
  • Data for Herrs Island Dam threshold days by year: CSV or JSON. Field meanings are on the data page.

Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-15 (15 October 2026). Records are computed by this site and are not official.

Data as of . Last revised (2025-12-31).