Dry conditions, wind and heat have notched up the forest fire risk across much of the northern half of Minnesota.

The state Department of Natural Resources (DNR) on Saturday said the fire risk is "high" in all or parts of 36 counties in central, east-central and northwestern Minnesota and declared the risk "very high" in Carlton County and the southern part of St. Louis County, which includes Duluth.

"We are seeing a drying trend throughout most of Minnesota," said Jean Goad, fire information officer at the Minnesota Interagency Fire Center based in Grand Rapids.

The DNR has restricted burning of brush and leaves in seven central and eastern counties, but campfires in designated fire rings are still allowed in state parks and recreation areas.

Southeastern Minnesota had a low fire risk. And the Boundary Waters Canoe Area Wilderness and Voyageurs National Park were rated at moderate risk.

Details about restrictions, updates and a fire risk map are on the DNR website via http://www.dnr.state.mn.us/forestry/fire/firerating_restrictions.html

All of the state's fire risk ratings are short of the top-level "Extreme," which officials said could trigger more concern and restrictions.

The National Weather Service has issued an excessive heat advisory, starting at noon Sunday and running through midnight Tuesday. Ninety-degree-plus temperatures are forecast through Tuesday in the Twin Cities.

The heat wave is expected to be accompanied by high humidity, which can inhibit forest fires. Fire officials said they are most worried when low relative humidity comes with high wind and heat. But excessive heat carries other hazards, such as an increased risk of heat stroke.

Goad said no major forest or brush fires were burning in Minnesota on Saturday.

The fire risk could change. High wind and a chance of rain in northernmost areas are factors that could affect the fire picture, according to Climate Prediction Center data.

Jay Cooke State Park near Carlton is within the very high fire risk region, but campfires were still allowed this weekend, said Mark Luschen, assistant park manager. "We have begun telling people to be more cautious with fire and making sure it's out," he said.

St. Croix State Park near Hinckley, suffered a major blowdown of trees in a July 2011 storm. But most of the downed trees have been logged off, reducing the risk of a wildfire, said assistant park manager Karl Sieve.

"The fire danger in the park is actually a lot less than what it was prior to the blowdown," he added.

David Shaffer • 612-673-7090 • @ShafferStrib