West Coast Heat Wave Clinches a Record Hot July in Seattle; Northeast Hot, But Not Historic

Chris Dolce
Published: July 31,2015
Summer heat is gripping opposite sides of the country into this weekend, including parts of the West and the Northeast.
The heat has helped to clinch one of the hottest Julys on record for some Northwest cities. It's also helped set a record for the most 90-degree days in a year in Seattle and has given Portland its hottest temperatures since 2009. After a hot weekend, some relief will finally arrive next week.
A substantial warm up is also occurring for places that saw snow earlier this week in Montana, Idaho and Wyoming.
The Northeast heat will not be as extreme, but it will stick around into next week for some cities.
Let's break down the forecast details on this summery weather pattern for both regions.

Northwest: Clinching a Record Hot July

Current Northwest Temperatures

Heat Alerts

A strong ridge of high pressure has built over the Northwest as the jet stream bulges northward to the Canadian border. This is allowing temperatures 5 to 20 degrees above average to take hold across parts of Oregon, Washington, Idaho and Montana this weekend
(MORE: Strange July Weather Pattern Brings Snow, Tornadoes)
It's a fitting end to one of the hottest Julys on record in parts of the Pacific Northwest. The following cities have clinched their hottest July on record (all data is preliminary and will be finalized August 1):

• Seattle: July 2015 average monthly temperature is 71.2 degrees. This beats the old July record of 69.5 degrees set in 2009.  Depending on the final data, this may have also beat out August 1967 (71.1 degrees) for the hottest of any month on record. Records date back to 1894.
• Eugene, Oregon: July 2015 average monthly temperature is 71.5 degrees. This beats the old July record of 71 degrees set in 1958. Records date back to 1912.
• Salem, Oregon: July 2015 average monthly temperature is 73.1 degrees. This beats the old July record of 72.5 degrees set in 2014. Records date back to 1893.

Portland, Oregon, has seen consecutive days with 100-degree heat, topping out at 103 degrees on Thursday and 101 degrees on Friday. Thursday's 103 was the hottest temperature there since July 29, 2009. Those hot temperatures have likely vaulted Portland to its second hottest July on record with an average temperature of 73.9 degrees, falling just behind 1985 which had an average of 74.1 degrees. Temperatures in Portland will be in the middle to upper 90s this weekend.
Seattle saw its eleventh 90-degree day of 2015 on Friday, which is a new record for the most 90-degree days in a calendar year. The old record was nine days set in 1958. Seattle averages just two days with 90-degree heat annually. The Emerald City could add to this record with temperatures forecast to be near 90 this weekend. A heat advisory has been issued by the National Weather Service for the Pudget Sound area through Saturday.
Eugene and Salem, Oregon, both set daily record highs on Thursday by topping out at 105 degrees. This was one degree shy of an all-time July record high in Eugene. Another daily record high of 103 degrees was set in Eugene on Friday. Highs are expected to be in the low 100s on Saturday followed by middle 90s Sunday.

Forecast Highs

Forecast Highs

Farther south, Roseburg, Oregon, was one degree short of an all-time record high on Thursday when it topped out at 108 degrees. Friday's high was 107 degrees.
For parts of central and eastern Washington, this round of hot temperatures probably won't be quite as intense as the late-June record-breaking heat wave. Spokane hit 105 degrees in late-June, but should hold near 100 degrees through the weekend.
In Northern California, Redding topped out at 114 degrees on Thursday, which set a new record for the date. Sacramento (downtown) set a daily record high of 107 degrees on Wednesday.
Boise, Idaho, will just squeak past 100 degrees for the next few days. Idaho's capital should fall well short of its June 28 high of 110 degrees, which set an all-time record for June.
For parts of Montana, this is quite a change from the way the week started.  For example, Missoula, Montana, saw rain with temperatures in the upper 40s and 50s on Monday afternoon. The high was in the low 90 degrees there on Thursday and Friday. Even hotter readings in the middle to upper 90s are possible this weekend.
High elevation areas that saw snow on Monday in the northern Rockies will also see significant temperature rises. Big Sky, Montana, could be near 80 degrees this weekend and Grand Targhee, Wyoming which saw 1.5 inches of snow early this week will see highs in the mid 80s this weekend.

Northwest Heat Relief Ahead

Some heat relief will finally arrive early next week in the Northwest. The entire region will see temperatures trend back to early-August averages Monday-Wednesday as the upper-level ridge responsible for the hot weather shifts east.
Highs of 80-84 degrees are anticipated in Seattle during the first half of the new week. Portland will see temperatures in the middle 80s Monday and Tuesday, followed by low 80s Wednesday.
Upper 90s and low 100s will also be eliminated from parts of eastern Washington, eastern Oregon, Idaho and western Montana as the new week begins.

Northeast: Heat Wave Possible in Some Cities

Forecast Highs

Wednesday was the hottest day so far in 2015 in New York City (96 degrees) and Albany, New York (95 degrees). Concord, New Hampshire, set a daily record high of 96 degrees, beating the old record for July 29 of 95 degrees set in 1949.
Highs will stay a handful of degrees above average for mainly eastern sections of the region into early next week.
For the most part, this heat in the Northeast will not be record breaking. However, the longevity of it will likely be greater than we've seen so far this summer in some cities. By early next week, some locations could meet the definition for a heat wave in the Northeast, which is generally defined in that region as three or more days in a row with temperatures at or above 90 degrees.
(MORE: Daily Forecast Maps)
That said, there is a big difference between the way it felt Thursday and the way it will feel into the weekend across the Northeast. This is because much drier air has filtered in behind a cold front that brought strong thunderstorms to the region on Thursday.
As a result, the humidity that has added to the discomfort dropped significantly, making the heat more bearable. For example, Washington, D.C. had an actual high of 92 degrees with a peak heat index of 103 degrees on Thursday. Friday's high was just as warm, but with lower humidity the heat index was not a factor.
New York City is likely to see highs mainly in the low 90s or upper 80s into early next week. So far this year, the Big Apple has experienced six days with 90-degree heat. Highs in the 90s were recorded on back-to-back days for just the second time this year on Tuesday and Wednesday.
Farther south, the Mid-Atlantic will sizzle through highs in the low to middle 90s into next week, including Washington, D.C., Baltimore and Philadelphia.
Washington, D.C. has already seen its fair share of 90s in 2015, with 33 days total through Friday. They will likely meet or exceed their annual average number of 90-degree days in the next few days which is 36.

MORE: Northern Rockies See July Snow