For at least the next couple days, get ready for an encore performance of summer weather.
Meteorologists at the National Weather Service in Medford predict temperatures in the 90s for today and Thursday, and possibly Friday, before the heat breaks and a cooling pattern returns.
“Normal is mid 70s for highs, so yes it is unusual. We expect it to be in the 90s on Wednesday, peaking Thursday,” said meteorologist Marc Spilde.
Spilde said Roseburg could see 90 degrees on Friday, but that depends on the timing of the onshore flow of colder air arriving that day. After that, he said, the temperatures should drop back to a more normal pattern.
High pressure off the Oregon and Washington coast and a low pressure system off the California coast is forcing warm air into the northwest.
“That’s inducing a thermal low pressure trough over northern California, and it’s basically warming the ground,” Spilde said.
The weather patterns have caused strong winds along with low humidity, Spilde said, fueling some fires in southern Oregon counties to become more active.
The Medford area is expecting some smoke from the fires that have blanketed the Rogue Valley this summer to return for a couple of days before the air flow changes and moves it out again.
But the high temperatures are not expected to last very long.
“The marine influence will win out eventually as the low pressure offshore gets closer to the coast, and when we see that move onshore this weekend, we’ll see a dramatic cool down,” Spilde said. “But whether or not that will produce rain is still in question.”
Although some rain is forecast for Saturday and Sunday, Spilde said not to expect much. And temperatures should drop to near normal after the heat wave leaves the area some time Friday.
The slight amount of rain in the forecast means little relief from drought conditions in the Umpqua Valley. Roseburg has recorded only 0.06 inch of rain in September, and all of that came on Sept. 12. Only 0.03 inch was recorded in August. No rain was recorded in the entire month of July.