Philadelphia Marathon could run into rain issues. Outlook for half-marathon chilly but not half bad.

While clouds are hanging over the weather forecast for Sunday’s annual Philadelphia Marathon, the outlook does have at least a few bright spots for participants.

Temperatures are forecast to range from 40 to 44 during the Sunday morning race, not too far from the ideal for most runners, says Jeremy Close, a sports medicine specialist at Jefferson University Hospitals and a runner himself.

Wind should not be a factor for at least the first part of the race, which begins at 7, said Sarah Johnson, lead meteorologist at the National Weather Service office in Mount Holly.

And the official forecast listed a better-than-even chance that the rain would shut off by race time Sunday. That said, rain right before the race could still be a pain for the runners milling about waiting for the race to get underway.

“The timing has been jumping around a bit,” said Johnson.

The rains would be generated by a coastal low that a month from now might look like a snow threat. Instead, it will be a rather ordinary cold November rain. Winds could pick up later in the race — maybe 5 to 15 mph with higher gusts, said Johnson — as the storm moves north.

And while Sunday morning might be chillier than the average spectator would like, it should be good for runners, Jefferson’s Close said.

Various studies have looked at optimal running weather conditions, including quite an extensive one that examined 10 years of marathons in Paris, London, Berlin, New York, Boston, and Chicago.

Essentially, upper 40s to low 50s is best, Close said; low- to mid-40s isn’t bad. And both beat running 26.2 miles in the heat.

“Running, you can talk about the ideal, but everything is rather personal,” Close said.

Some might even enjoy running in the rain.

For those not running or watching, temperatures should be ideal for sleeping.