NAM model radar simulation indicates light to moderate rain over Washington, D.C. at 10 a.m. Saturday morning.

With 30,000 runners hitting the streets of Washington, D.C. Saturday morning for the Rock’n’Roll marathon and half marathon, the weather forecast looms large. Unfortunately, it looks cool and wet.

Link: Rock ‘n’ Roll Marathon closures, Metro advisories

A little wave of low pressure will zip into the region early Saturday morning. For the race’s start time at 7:30 a.m., rain may not have yet begun, but by around 9 a.m., rain is likely. The rain shouldn’t be particularly heavy, but may well fall steadily between 8:30 a.m. and 1 p.m. or so. Amounts will probably be around 0.1-0.2 inches.

It will be a chilly rain too, with temperatures in the low 40s to begin and only rising into the mid-40s by the race’s conclusion early afternoon.

Winds out of the north and northeast at around 5-10 mph shouldn’t be a major factor.

Here’s a graph showing predicted temperartures, rain, and wind from the National Weather Service during the day Saturday.

For marathon newbies, here are a couple good resources that provide tips for running in rain and cold rain:

Runner’s World: Marathon in the rain tips

New York Daily News: Expert tips for running in the rain