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.
