Yakima, Washington, Ties All-Time June Heat Record as Pacific Northwest Sizzles (FORECAST)

June 8,2015

An unseasonably early heat wave kicked into high gear over the Pacific Northwest Monday, sending at least one city to its highest temperature ever recorded in the month of June.

Current Temperatures

Yakima, Washington, topped out at 105 degrees as of 5 p.m. PDT Monday. That ties the city's all-time June heat record set June 23, 1992; importantly, it comes 15 days earlier on the calendar, making it by far the earliest 105-degree reading on record there.
Record heat will persist through at least the middle of the week in the Pacific Northwest. High temperatures will generally be 10 to 25 degrees warmer than usual for this time of year. Several cities may see the hottest weather ever recorded this early in the year.
Such high temperatures can become dangerous for those exposed to the elements for lengthy amounts of time, as heat exhaustion and dehydration may set in. Be sure to drink plenty of water, and schedule plenty of rest in cool, dry areas.
According to preliminary data, two of the nation's hottest locations Sunday were in the Northwest. The mercury topped out at 106 degrees near Hermiston, Oregon, and at the Chief Joseph Dam in north-central Washington. Tacna, Arizona, was the only other spot in the nation to hit 106. By contrast, Death Valley in California only hit 105.

Forecast Highlights

Forecast Highs

Current Heat Alerts

Triple-digit heat is expected to continue over parts of Washington and Oregon into Tuesday.
That would make three triple-digit days in a row for Yakima, which smashed the former record of 96 degrees (set in 1977) when the thermometer broke the century mark Sunday and hit 101.
Besides the historic record high in Yakima Monday, other triple-digit highs in the region (based on preliminary data) included 104 in Hermiston, Oregon, and Pasco, Washington; 102 in Ephrata, Wenatchee and Walla Walla in Washington; 102 in The Dalles and Pendleton, Oregon; 101 in Moses Lake, Washington; and 100 in Omak, Washington, a mere 40 miles south of the Canadian border.
(MAPS: 10-day Forecast)
Most areas in Washington and Oregon, however, will not see temperatures over 100 degrees. Those readings will remain confined to the Lower Columbia Basin and parts of the Yakima Valley, as well as the Rogue Valley of southwest Oregon, where Medford hit 105 Monday. That's the earliest Medford has been that hot since a 109-degree high on June 6, 1926.
Parts of the Sacramento Valley of northern California will also continue soaring into the 100s in the days to come. Some locations that are expected to tie or break daily high temperature records include:

• Redding, California: Highs hit 102 degrees on Saturday, 105 degrees on Sunday and a preliminary 107 degrees Monday. Redding is forecast to hit 100+ degrees again Tuesday, possibly beating the record high of 104 for June 9.
• Spokane, Washington: After a high of 91 degrees on Sunday and a daily record high of 94 Monday, thermometers are expected to continue the trend of reaching the low to mid-90s on Tuesday, challenging the standing record of 93.

The heat will also spread across Idaho, Montana and into the Dakotas as the week goes on. A few daily record highs may fall in Idaho and Montana Tuesday as well.
(MORE: Record Heat in March for Parts of the West)

Monday's Highs and Departure From Average

Boise, Idaho will see temperatures surge well into the 90s, possibly breaking the record high of 98 degrees for Tuesday.
Missoula, Montana will also be in reach of current records on Tuesday (90 degrees).
Seattle and Portland, Oregon will also see temperatures warmer than expected for this time of year. Highs in Seattle will climb into the 80s, with Portland likely reaching the low 90s or upper 80s Tuesday. The average high in Seattle for early June is in the upper 60s, and Portland usually sees highs in the lower 70s. This warm spell comes after the warmest winter on record in both Seattle and Portland.
(MORE: Warmest Winter on Record)
One other interesting tidbit regarding this heat: Temperatures in mid-levels of the atmosphere will flirt with the warmest readings ever seen during the first half of June and may even near all-time records for the month, according to the National Weather Service in Spokane.

What is Causing the Record Heat and How Long Will It Last?

So what is the culprit for this potentially record-breaking heat?
A strong upper-level ridge has built in from the Pacific, covering much of the Northwest since Saturday and continues early this week. This ridge of high pressure is leading to drier and much warmer conditions.
As this area of high pressure begins to slowly slide east, the core of the heat will move east as well.
(MAPS: Weekly Planner)
The good news is that somewhat cooler air gradually returns by midweek.
A shortwave trough will pass through western Canada, which will push a weak, but dry cold front through the region. Meanwhile, weak troughing is expected to develop off the West coast. This will lead to a gradual cooling trend. However, temperatures will still likely remain above average through the week.
This subtle pattern change may also draw some moisture back northward and result in a slight chance of showers or thunderstorms midweek.
MORE: Dozens Hospitalized During L.A. Marathon Due to Record Heat