Southern Oregon heads into a mostly sunny and increasingly warm week, with dry highways expected across much of the region and temperatures climbing into the 90s in parts of the Rogue Valley before cooling slightly for the weekend.
Monday, September 14, begins the stretch with sunshine across Josephine and Jackson counties and cooler conditions east of the Cascades. Grants Pass will finish the day near 80 degrees before temperatures fall into the upper 40s overnight. Klamath Falls will be substantially cooler, with daytime temperatures near 70 and overnight readings dropping into the middle 30s. Interstate 5 through Grants Pass, Medford and Ashland should remain dry, including the higher sections approaching Sexton Mountain and Siskiyou Summit.
Tuesday brings a noticeable warmup to western Southern Oregon. Grants Pass is expected to reach about 87 degrees under partly to mostly sunny skies, with morning temperatures near 50. Klamath Falls will warm into the middle 70s following another chilly morning. Dry pavement and good visibility are expected along most major travel corridors, including Interstate 5, Highway 199 and routes connecting the Rogue Valley with communities east of the Cascades.
Wednesday continues the warm pattern in Grants Pass and the Rogue Valley, where afternoon temperatures should again reach the upper 80s beneath abundant sunshine. The weather becomes less settled east of the Cascades, where portions of the Klamath Basin could see an isolated afternoon thundershower. Travelers heading toward Klamath Falls and communities farther east should be prepared for localized rainfall, gusty winds or brief changes in visibility if thunderstorms develop.
Thursday pushes temperatures into the 90s around Grants Pass, with mostly sunny skies and an afternoon high near 91 degrees. Klamath Falls remains considerably cooler, reaching only the lower 70s. The contrast will be especially noticeable for motorists traveling between the Rogue Valley and the high desert, where morning temperatures can be several dozen degrees colder than afternoon readings west of the Cascades. Interstate 5 conditions through Josephine and Jackson counties are expected to remain dry.
Friday is positioned to become the hottest day of the week in the Grants Pass area, with sunshine and temperatures near 92 degrees. Morning temperatures should remain near 50, producing a sharp warmup through the afternoon. Klamath Falls will reach the middle 70s. Travelers making longer trips through the Rogue Valley should be prepared for midsummer-like afternoon heat despite the calendar moving into the second half of September.
Saturday brings some relief from the heat without a major change in the overall weather pattern. Grants Pass is forecast near 84 degrees with plenty of sunshine, while Klamath Falls reaches the upper 70s. Dry conditions should continue along Interstate 5 from northern Josephine County through Medford, Ashland and Siskiyou Summit, giving weekend travelers favorable conditions for trips through Southern Oregon and into Northern California.
Sunday closes the week with another mostly sunny day. Grants Pass should remain near 84 degrees, while Klamath Falls warms to around 82. Overnight temperatures will continue falling into the 40s and lower 50s west of the Cascades and considerably colder levels in some higher-elevation and high-desert locations.
For Southern Oregon travelers, the week is shaping up with few widespread weather problems along the major highways. The greatest weather variable arrives Wednesday east of the Cascades, where isolated thunderstorms could briefly affect travel. The Rogue Valley’s primary concern will instead be the sharp rise in afternoon temperatures Thursday and Friday.
Drivers traveling Interstate 5 should continue checking current conditions around Sexton Mountain, Smith Hill and Siskiyou Summit before departure. Highway 199 travelers heading toward the coast and motorists using Highway 62 toward Crater Lake should also account for elevation changes that can produce cooler temperatures and different conditions than those experienced in Grants Pass or Medford.
Overall, Southern Oregon will move through the week under a predominantly dry late-summer pattern, beginning comfortably Monday, heating considerably through Friday and settling back into the 80s for a sunny weekend.