The National Weather Service in Medford says high temperatures could threaten the 100-degree mark as Rogue Valley residents head into the weekend.

Temperatures in Medford could flirt with the century mark on Friday, according to an NWS-Medford post early Tuesday.

“Our stretch of well above normal highs and dry conditions starts today and will go through the end of May,” the forecast discussion post said. “This may result in a period of excessive heat, especially Friday through Saturday. While a small chance for showers and thunderstorms exists on Wednesday, coverage will be very isolated and may not impact many areas.

“Our next decent chance for rainfall isn’t until early next month,” the post continued. “In fact, early indications point towards a cool and perhaps showery start to June.”

Daytime highs are expected to hit 92 Tuesday in Medford, with a high of 91 on Wednesday and a cooler 85 on Thursday, still above average for this time of year, forecasters noted. Areas from Ashland to Grants Pass are expected to see highs in the upper 80s Tuesday and Wednesday before Thursday’s cooldown.

By Friday, however, cities across the region could bake under higher temperatures, with Medford forecast for a high of 97 Friday and 91 Saturday, and Ashland and Grants Pass pegged at 94 Friday and temperatures reaching into the upper 80s by Saturday, the post said.

More seasonal temperatures are expected to return by Sunday, according to the NWS-Medford website.

“This will be the start of a couple notable warm afternoons when heat could pose a risk to people outdoors,” forecasters warned. “This is especially true for vulnerable populations (e.g. people with no access to cooling, older/younger people, animals, etc.) through this stretch of hot temperatures. There will be places that may reach 100 degrees each of these days albeit in very isolated areas. There will be plenty of areas in the mid to upper 90s.”

NWS forecasters also warned of low humidity levels.

“This will be our first notable heat wave this year. This well will also be noted by very dry conditions with daily humidity values dropping down to the teens and 20 percent range for many areas inland, especially the eastside and some westside valleys. Now is a good time to brush up on fire safety and fire mitigation tactics as we head into fire season which starts June 1st.”