A hot and stormy Saturday may put a damper on weekend plans in the Twin Cities, while runners in Duluth could face heavy rain during popular Grandma’s Marathon events.

An excessive heat warning remained in effect for the seven-county metro until 8 p.m. Saturday, with rounds of heavy rain and severe weather also possible.

The National Weather Service said Friday that the “combination of hot temperatures and high humidity will combine to create a dangerous situation in which heat illnesses are likely.” Weather officials advised residents to drink plenty of water, stay indoors if possible and check on relatives and neighbors.

Friday brought dangerous heat to the metro area and thunderstorms farther north, with Duluth facing flooded streets, downed power lines and canceled youth races on the eve of the popular Grandma’s Marathon.

A Friday afternoon storm in Duluth left a foot of water near the intersection of Garfield Avenue and West Railroad Street and 8 to 10 inches at 27th Avenue W. and West Michigan Street, according to the Weather Service. There were also reports of downed trees and power lines in the area.

The nasty storms forced Grandma’s Marathon to scrap Friday’s Whipper Snapper Races. The short dashes for children were scheduled to begin at 2 p.m. The annual William A. Irvin 5K was held Friday evening as planned.

A flash flood watch remained in effect in St. Louis County and several surrounding counties through Sunday morning.

In the Twin Cities, showers and thunderstorms were possible into the night and on Saturday morning, according to the Weather Service.

Saturday will bring a 50 percent chance of showers and thunderstorms in the Twin Cities, mainly before 1 p.m. The high will be near 95, with heat index values as high as 102.

Saturday night will bring another chance of rain, mostly after 7 p.m., with an overnight low around 76.

Sunday — Father’s Day — will also be stormy, with heavy rainfall possible in some areas. Sunday’s high will be near 90, with a heat index value as high as 97.

Rain is possible again Monday, with ample sunshine and more reasonable highs in the 80s returning Tuesday and Wednesday.