A list of Tri-Cities temperature records broken by this week’s heat wave

Final update: July 2, 2021 at 06:10 PDT. Details below.

As we head into July, the heat wave that gripped the region over the past week or so is waning. It leaves behind numerous new temperature records throughout the Pacific Northwest as well as possibly hundreds of deaths and some large wildfires.

This article is a numbers heavy list of the temperature records broken in the Tri-Cities during the Great Northwest Heatwave that uses many tables. The current primary climate site for the Tri-Cities is the Tri-Cities Airport in Pasco, though it has previously been in nearby parts of Kennewick and Pasco. At the bottom will be a list of other records nearby (including Richland’s possible new state record).

Note that some records will be repeated in different categories. Unless otherwise noted, these records represent record maximum temperatures.


HIGH TEMPERATURES
Records begin 1894.

All-time

Date New record Old record (year)
June 27 115° (tie) 115° (1898, 1939)

Monthly

Date New record Old record (year)
June 27 115° 111° (2015)

Daily

Date New record Old record (year)
June 26 110° 105° (1925, 2015)
June 27 115° 111° (2015)
June 28 114° 111° (2015)
June 29 113° 107° (1904)
June 30 113° 106° (1924)

Consecutive days

Threshold Days above (rank) Old or current record (year)
110° 5 (1st) 2 (multiple)
105° 5 (2nd) 6 (1911)
100° 5 (32nd) 10 (1967)

Other records

  • June 2021 average high temperature: 92.6° (ranked 2nd – current record: 92.7° in 2015). Climatological June average high is 83.2°.
  • June 15-30 average high temperature: 98.9° (ranked 1st – old record: 96.1° in 1896). Climatological average for this period is 85.0°.
  • Second earliest 110°+ high temperature: June 26 (current record is June 7 set in 1912).
  • Five of the ten hottest June days on record occurred in 2021.
  • Four of the ten hottest days on record (regardless of month) occurred during the heatwave.

DAILY MEAN TEMPERATURES
Records begin 1894.

Monthly

Date New record Old record (year)
June 30 93.5° 92.5° (1896)

Daily

Date New record Old record (year)
June 28 92.0° 90.0° (2015)
June 29 91.0° 88.5° (2015)
June 30 93.5° 88.5° (2008)

Other record

  • June 2021 average daily mean temperature: 75.7° (ranked 1st highest – old record: 75.3° in 2015). Climatological June average: 68.2°.

LOW TEMPERATURES
Records begin 1894.

Thanks to strong overnight inversions and the fact that the Tri-Cities Airport is a low elevation site, no daily, monthly, or all time maximum low temperatures were recorded. Stations at higher elevations, however, had some nights with lows just barely below 90°.


HOURLY TEMPERATURES
Records begin 1945.

Hottest ever recorded at the given hour

Hour of day New record Date
04 85° June 30
06 83° June 30
07 85° June 30
08 88° June 30
09 91° June 30
10 96° June 28
11 99° June 28
12 103° June 28
13 106° June 28
14 109° June 30
16 115° June 27
21 101° June 29
23 95° June 27


POSSIBLE ALL-TIME STATE HIGHS
Washington

These are considered preliminary. NOAA and other agencies are investigating these records to determine which one (if any) is the new state record. The current official record is 118°.

Location Temperature
Hanford 100 Area 120°
WSDOT Beloit Hanford 119°
WSDOT Horn Rapids 119°
WSDOT Twin Bridges 119°
AWN Benton City East 118°
Dallesport 118°
Hanford Met. Station 118°
Richland Airport 118°


POSSIBLE ALL-TIME STATE HIGHS
Oregon

These are considered preliminary. NOAA and other agencies are investigating these records to determine which one (if any) is the new state record. The current official record is 119°, but that value is disputed. It is more likely that the record is 117°, which is the number I will use for this table.

Location Temperature
Celilo 121°
Pelton Dam 119°
Hermiston 118°
Maupin 117°
Pendleton 117°
Salem 117°


ALL-TIME CITY HIGHS
Select Inland Northwest locations

Location New record Old record (year)
Ephrata 116° 115° (1961)
Hermiston 118° 111° (2015)
Pendleton 117° 114° (1928)*
Spokane 109° 108° (1961)
The Dalles 118° 111° (1998)
Walla Walla 116° 114° (1975)
Wenatchee 114° 109° (1961, 2015)
Yakima 113° 110 (1941)


*The official record high at Pendleton is 119°, but this value is disputed.

Data in this post was sourced from the National Oceanic and Atmospheric Administration, Iowa Environmental Mesonet, and WSU AgWeatherNet with help from Chris Callais. I will update this post over the next couple days as needed. Thanks for reading and enjoy the cooler temperatures!

July 2 update: July 1 saw a high of 99°, ending the 100°+ streak. Edited the consecutive days section to reflect this.

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