A string of warm, sunny days expected to continue through this weekend has prompted the Oregon Department of Forestry to declare that fire season will start in Jackson and Josephine counties on July 1.

A string of warm, sunny days expected to continue through this weekend has prompted the Oregon Department of Forestry to declare that fire season will start in Jackson and Josephine counties on July 1.

The date matches the latest start for fire restrictions, records show. The fire season in 1998 also started July 1. In 2009, fire season started June 19. April 18, 1988, saw the earliest start date for fire season since ODF started keeping track in 1967.

Assistant district forester Greg Alexander said a wet spring that brought lots of rain and even mountain snow in May and June helped delay this year's fire season.

Foresters start the fire season when vegetation becomes dry and fires become harder to control.

"It's still a lot of moisture at higher elevations, but in the valley, the grass is starting to cure out," he explained.

A persistent trough of low pressure that kept the weather cool here even as the calendar turned to summer will head east, clearing the way for a ridge of high pressure — and the higher temperatures it brings — to build over the West Coast, said Marc Spilde, a meteorologist at the National Weather Service's Medford office.

Temperatures in the Rogue Valley likely will hit 90 today and edge into the low to mid-90s on Sunday. Sunday likely will be the warmest day, as another disturbance moves in early next week.

A push of marine air will send temperatures back below normal Tuesday through Thursday, the forecaster said. Spilde expects high temperatures to hover in the upper 70s, possibly reaching 80.

Alexander noted that the wet spring promoted a lush growth of grasses and other seasonal plants.

"If that dries out, it could burn fast, but if the summer stays mild and we get some showers later, it might stay lush," he said. "We could have a mellow fire season or a difficult one."

Whatever nature brings, people have an important role in preventing fires, Alexander said. Paying attention to the latest fire restrictions and being careful with tasks, tools or toys that could spark a blaze can make a difference in the number of fires this summer.

People burning one last round of debris this weekend before restrictions start should be especially careful as temperatures rise, he said.

Fire danger is currently low, but will shift to moderate on Thursday. With the start of fire season, debris burning will be prohibited, as will the use of fireworks in the forest. Commercial timber harvesting operations will be required to have fire-suppression equipment and a watchman on the job site at all times.

In the Wild and Scenic section of the Rogue River between Grave Creek and Marial campfires must be in fire pans or on a fire blanket in vegetation-free areas on sand or gravel bars between the river and the high-water mark. Smoking is limited to on the river and vegetation-free areas, as well. Fireworks are prohibited, and travelers must carry a shovel and a bucket.

The latest fire season information always is available online at www.oregon.gov/ODF/FIELD/SWO/SWOfire.shtml.

Reach reporter Anita Burke at 541-776-4485, or e-mail aburke@mailtribune.com.