As runners prepare for the weekend, they will be keeping an eye on the weather.

The Mill Race Marathon opens today with the fifth annual Kids Fun Run, which already has more than 1,000 children signed up to compete in one of five age-level heats, starting at 6 p.m. at Mill Race Park.

It’s good that the distances are short — from about one-tenth of a mile for the youngest to just over a mile for the oldest — because it’s going to be warm. The temperature is forecast to be 86 for today’s 6 p.m. start.

To sign up your child for the Fun Run, register online, in person at The Commons (300 Washington St.) from 10 a.m. to 4 p.m. or at Mill Race Park (50 Carl Miske Drive) from 4:45 until 5:45 p.m. There is no entry fee for the Kids Fun Run.

Registration is open for Saturday’s Mill Race Marathon, half-marathon or 5K until race day. Fees are $95 for the full marathon, $80 for the half-marathon and $30 for the 5K.

Similar weather conditions will prevail Saturday. When races kick off Saturday morning, temperatures are forecast to be in the mid 60s before warning to the mid-80s by noon.

About 4,400 runners have already signed up to participate this weekend in Columbus.

Register at millracemarathon.com.