UPDATED 2025 Grandma’s Marathon Weekend Weather Forecast

UPDATE: Race officials have provided a statement about expected severe weather overnight and how it will impact race day. You can read that information here. 

Duluth is getting ready to welcome thousands of runners for the three major events of Grandma's Marathon Weekend this Friday and Saturday.

The new afternoon time for the William A. Irvin 5K on Friday, along with new times for some of the music at Bayfront Festival Park, plus with the normal timeframes for Saturday's Garry Bjorklund Half Marathon, Grandma's Marathon, and post-race music will see lots of people curious about how the weather will cooperate with this year's events.

READ MORE: See the 2025 free music lineup for Grandma's Marathon Weekend

While things can certainly change in a short timeframe with the weather around the Duluth area, things are looking promising for Saturday's big day. There are some rain and thunderstorm chances to be aware of (mostly later Friday), but Saturday's events shouldn't face any major weather challenges.

Here's an event-by-event look at the weather for the weekend's festivities.

Friday Afternoon - William A Irvin 5K, Kids Events

Mostly cloudy with temperatures around 60 degrees in Canal Park and near Lake Superior. It will be warmer away from the lake. An east (lake) breeze of 10-15 mph is the reason for these cooler conditions.

Friday Evening - Entertainment Concert (Duluth)

Mostly cloudy with temperatures in Canal Park and near Lake Superior in the upper 50s due to a persistent east breeze of 10-15 mph. The threat of rain and thunderstorms is expected mainly after live music wraps up at 7:30 Friday night.

Rain and thunderstorm chances increase late in the evening hours, with a likelihood of thunderstorms, some of which could be severe, late overnight.

Saturday Morning - Grandma's Marathon Starting Line (Two Harbors)

Rain is likely in the overnight hours, with a significant chance of strong to severe thunderstorms overnight and into the early morning hours on Saturday. As of right now, the greatest threat of these storms looks to wrap up by around race start time, so everyone will have to monitor the latest from race organizers about any potential impacts.

Temperatures will be in the upper 50s at race start time, with slight rain or thunderstorm chances through the morning hours. An east (lake) breeze of 5-10 mph is expected.

READ MORE: What is "normal" weather for Grandma's Marathon? Here's a historical look

Saturday Morning - Gary Bjorklund Half Marathon/Grandma's Marathon Finish Line (Duluth)

As the morning's rain/storms move out, decreasing clouds are expected through the morning hours, with partly cloudy conditions expected later into the morning. Temperatures will warm to near 67 degrees by 10 am and to near 72 by noon.

An east (lake) breeze of 5-10 mph is what will keep conditions a little cooler along the race course than they will be away from Lake Superior.

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Saturday Daytime (Duluth)

Mostly clear conditions are expected by afternoon, with temperatures getting up to around 80 degrees in Canal Park by mid-afternoon. There will be a lake breeze, continuing to keep it a little cooler by the lake as compared to the warmer conditions expected away from Lake Superior. There are no major rain chances through the afternoon.

Saturday Evening - Entertainment Concerts (Duluth)

A slight increase in clouds to see partly cloudy conditions into the evening, with temperatures going from around 75 degrees at 6 pm to the mid-60s by 10 pm. There are no significant rain chances through the evening with a lake breeze of 5-10 mph through the evening.