Lower Monumental Dam Weather Records (USC00454841)

Record envelope, standing records and threshold days for Lower Monumental Dam (USC00454841), Washington, United States, with 46 years of record.

Key Facts for Lower Monumental Dam

Lower Monumental Dam (USC00454841) is a weather station in Washington, United States at 46.56 latitude and -118.54 longitude, 140 m (460 ft) above sea level.
The station reports from 1962 to 2007, 46 years of record.
1,464 records set at Lower Monumental Dam still stand.
Records are tracked for no element yet: an element needs 30 years of data to be eligible.

About the Station

Location: Washington, United States, 46.56 latitude, -118.54 longitude.
Elevation: 140 m (460 ft).
Period of record: 1962 to 2007, 46 years.
Eligible elements: none yet.

Daily Record Envelope and 2026

0 days at or beyond a record

The band shows the record high and record low for each calendar day at Lower Monumental 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 Lower Monumental Dam, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	18.3 C (64.9 F)	-21.1 C (-6.0 F)	n/a	n/a
Feb	21.1 C (70.0 F)	-12.8 C (9.0 F)	n/a	n/a
Mar	25.6 C (78.1 F)	-8.3 C (17.1 F)	n/a	n/a
Apr	32.8 C (91.0 F)	-2.2 C (28.0 F)	n/a	n/a
May	38.9 C (102.0 F)	2.2 C (36.0 F)	n/a	n/a
Jun	41.1 C (106.0 F)	4.4 C (39.9 F)	n/a	n/a
Jul	43.9 C (111.0 F)	8.3 C (46.9 F)	n/a	n/a
Aug	42.8 C (109.0 F)	6.7 C (44.1 F)	n/a	n/a
Sep	40.6 C (105.1 F)	-0.6 C (30.9 F)	n/a	n/a
Oct	31.1 C (88.0 F)	-5.6 C (21.9 F)	n/a	n/a
Nov	22.8 C (73.0 F)	-10.6 C (12.9 F)	n/a	n/a
Dec	16.7 C (62.1 F)	-25.6 C (-14.1 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Lower Monumental Dam still stand. 1969 holds the most, with 108.

Standing records at Lower Monumental Dam by the year they were set
Year set	Standing records
1962	25
1963	106
1964	95
1965	91
1966	88
1967	105
1968	95
1969	108
1970	72
1971	94
1972	104
1973	68
1974	66
1975	73
1976	66
1977	67
1978	80
1979	20
2005	11
2006	27
2007	3

Wettest Day of Each Month

Jun: 31.0 mm (1.2 in)

The wettest day on record for each calendar month at Lower Monumental Dam. The most was 31.0 mm (1.2 in) on 18 June 1965.

Record daily precipitation for each month at Lower Monumental Dam
Month	Record daily precipitation (mm)	Date
Jan	17.8 mm (0.7 in)	26 January 1975
Feb	16.3 mm (0.6 in)	13 February 1970
Mar	25.4 mm (1.0 in)	29 March 1967
Apr	24.4 mm (1.0 in)	20 April 1970
May	24.6 mm (1.0 in)	22 May 1972
Jun	31.0 mm (1.2 in)	18 June 1965
Jul	20.6 mm (0.8 in)	13 July 1975
Aug	18.8 mm (0.7 in)	30 August 1977
Sep	20.1 mm (0.8 in)	14 September 1966
Oct	19.1 mm (0.8 in)	19 October 1979
Nov	27.4 mm (1.1 in)	2 November 1968
Dec	19.3 mm (0.8 in)	14 December 1977

Period of Record Coverage

1962 to 2007

21 years of record at Lower Monumental Dam, 1962 to 2007. 6 years have data for under 90 percent of days and are left out of rankings: 1962, 1975, 1979, 2005, 2006, 2007.

Days with data per year at Lower Monumental Dam
Year	Days with data	Share of year	Complete
1962	92	25%	No
1963	365	100%	Yes
1964	366	100%	Yes
1965	365	100%	Yes
1966	362	99%	Yes
1967	364	100%	Yes
1968	330	90%	Yes
1969	364	100%	Yes
1970	361	99%	Yes
1971	365	100%	Yes
1972	335	92%	Yes
1973	334	92%	Yes
1974	333	91%	Yes
1975	303	83%	No
1976	366	100%	Yes
1977	334	92%	Yes
1978	365	100%	Yes
1979	31	8%	No
2005	118	32%	No
2006	137	38%	No
2007	7	2%	No

Latest Records

No records were set at this station in the latest data.

Climate Trend

10 complete years, 1963 to 1978

One stripe for each of 10 complete years at Lower Monumental Dam, 1963 to 1978. Blue stripes are years cooler than the station's own mean of 12.6 C (54.7 F); red stripes are warmer. The coolest year was 1978, at 11.2 C (52.2 F), and the warmest was 1967, at 14.0 C (57.2 F). The strongest colour marks a difference of 1.4 C (2.5 F).

Annual mean temperature at Lower Monumental Dam as warming stripes, 1963 to 1978
Year	Annual mean temperature	Difference from the station mean
1963	12.5 C	-0.18 C
1964	12.0 C	-0.66 C
1965	13.2 C	+0.52 C
1966	13.5 C	+0.91 C
1967	14.0 C	+1.38 C
1969	12.4 C	-0.22 C
1970	12.8 C	+0.15 C
1971	12.5 C	-0.09 C
1976	12.2 C	-0.46 C
1978	11.2 C	-1.39 C

This station does not have enough complete years (30 are needed) to fit a temperature trend.

A year is complete when all 12 months have at least 20 days of both daily maximum and daily minimum readings. The annual mean is the mean of the monthly means. The trend describes this one station over this period; it does not say what caused the change.

Extremes by Year

1962 to 2007

Yearly extremes at Lower Monumental Dam: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	43.9 C (111.0 F)	1975	41.7 C (107.1 F)	21
Coldest night (TNn)	-25.6 C (-14.1 F)	1968	-11.1 C (12.0 F)	21
Wettest day (Rx1day)	31.0 mm (1.2 in)	1965	16.8 mm (0.7 in)	22
Wettest five days (Rx5day)	50.5 mm (2.0 in)	1977	31.0 mm (1.2 in)	22
Longest dry spell (CDD)	110 days	1974	43 days	22

Hottest day (TXx)

The hottest day of the year at Lower Monumental Dam, 1962 to 2007. The record is 43.9 C (111.0 F) in 1975, marked on the chart; the median year is 41.7 C (107.1 F).

Hottest day (TXx) at Lower Monumental Dam by year
Year	Hottest day (TXx)
1962	26.7 C (80.1 F)
1963	39.4 C (102.9 F)
1964	41.7 C (107.1 F)
1965	42.8 C (109.0 F)
1966	40.6 C (105.1 F)
1967	42.8 C (109.0 F)
1968	42.8 C (109.0 F)
1969	38.9 C (102.0 F)
1970	42.8 C (109.0 F)
1971	42.2 C (108.0 F)
1972	42.8 C (109.0 F)
1973	41.7 C (107.1 F)
1974	42.2 C (108.0 F)
1975	43.9 C (111.0 F)
1976	39.4 C (102.9 F)
1977	41.7 C (107.1 F)
1978	42.2 C (108.0 F)
1979	1.7 C (35.1 F)
1980	n/a
2005	38.3 C (100.9 F)
2006	36.7 C (98.1 F)
2007	17.8 C (64.0 F)

Coldest night (TNn)

The coldest night of the year at Lower Monumental Dam, 1962 to 2007. The record is -25.6 C (-14.1 F) in 1968, marked on the chart; the median year is -11.1 C (12.0 F).

Coldest night (TNn) at Lower Monumental Dam by year
Year	Coldest night (TNn)
1962	-8.3 C (17.1 F)
1963	-17.2 C (1.0 F)
1964	-21.1 C (-6.0 F)
1965	-8.3 C (17.1 F)
1966	-6.1 C (21.0 F)
1967	-10.6 C (12.9 F)
1968	-25.6 C (-14.1 F)
1969	-18.9 C (-2.0 F)
1970	-8.9 C (16.0 F)
1971	-8.9 C (16.0 F)
1972	-18.3 C (-0.9 F)
1973	-15.0 C (5.0 F)
1974	-17.2 C (1.0 F)
1975	-11.1 C (12.0 F)
1976	-8.3 C (17.1 F)
1977	-10.6 C (12.9 F)
1978	-20.6 C (-5.1 F)
1979	-21.1 C (-6.0 F)
1980	n/a
2005	-12.2 C (10.0 F)
2006	-6.1 C (21.0 F)
2007	-2.8 C (27.0 F)

Wettest day (Rx1day)

The wettest day of the year at Lower Monumental Dam, 1962 to 2007. The record is 31.0 mm (1.2 in) in 1965, marked on the chart; the median year is 16.8 mm (0.7 in).

Wettest day (Rx1day) at Lower Monumental Dam by year
Year	Wettest day (Rx1day)
1962	13.7 mm (0.5 in)
1963	15.7 mm (0.6 in)
1964	15.7 mm (0.6 in)
1965	31.0 mm (1.2 in)
1966	21.1 mm (0.8 in)
1967	25.4 mm (1.0 in)
1968	27.4 mm (1.1 in)
1969	17.8 mm (0.7 in)
1970	24.4 mm (1.0 in)
1971	15.7 mm (0.6 in)
1972	24.6 mm (1.0 in)
1973	20.3 mm (0.8 in)
1974	7.4 mm (0.29 in)
1975	20.6 mm (0.8 in)
1976	9.4 mm (0.37 in)
1977	19.3 mm (0.8 in)
1978	14.7 mm (0.6 in)
1979	19.1 mm (0.8 in)
1980	8.9 mm (0.35 in)
2005	11.9 mm (0.5 in)
2006	15.7 mm (0.6 in)
2007	3.8 mm (0.15 in)

Wettest five days (Rx5day)

The wettest five days of the year at Lower Monumental Dam, 1962 to 2007. The record is 50.5 mm (2.0 in) in 1977, marked on the chart; the median year is 31.0 mm (1.2 in).

Wettest five days (Rx5day) at Lower Monumental Dam by year
Year	Wettest five days (Rx5day)
1962	30.7 mm (1.2 in)
1963	30.4 mm (1.2 in)
1964	48.7 mm (1.9 in)
1965	31.5 mm (1.2 in)
1966	44.5 mm (1.8 in)
1967	33.0 mm (1.3 in)
1968	28.4 mm (1.1 in)
1969	20.6 mm (0.8 in)
1970	39.4 mm (1.6 in)
1971	29.5 mm (1.2 in)
1972	31.2 mm (1.2 in)
1973	35.1 mm (1.4 in)
1974	22.1 mm (0.9 in)
1975	32.8 mm (1.3 in)
1976	19.4 mm (0.8 in)
1977	50.5 mm (2.0 in)
1978	29.6 mm (1.2 in)
1979	29.0 mm (1.1 in)
1980	13.5 mm (0.5 in)
2005	31.8 mm (1.3 in)
2006	47.8 mm (1.9 in)
2007	4.4 mm (0.17 in)

Longest dry spell (CDD)

The longest dry spell of the year at Lower Monumental Dam, 1962 to 2007. The record is 110 days in 1974, marked on the chart; the median year is 43 days.

Longest dry spell (CDD) at Lower Monumental Dam by year
Year	Longest dry spell (CDD)
1962	20 days
1963	69 days
1964	50 days
1965	41 days
1966	62 days
1967	81 days
1968	42 days
1969	85 days
1970	34 days
1971	43 days
1972	30 days
1973	98 days
1974	110 days
1975	30 days
1976	59 days
1977	40 days
1978	41 days
1979	44 days
1980	12 days
2005	19 days
2006	44 days
2007	22 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.

Download the Data

Data for Lower Monumental Dam standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Lower Monumental 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 2026-10-14 (14 October 2026). Records are computed by this site and are not official.

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