Metro residents who venture out Sunday morning need to remember the Publix Georgia Marathon and Half Marathon. The races, which begin at 7 a.m., could cause traffic snarls throughout the area.

There's also the prospect of rain drenching the area by mid- to late morning, causing headaches for road workers putting the finishing touches on the new Ga. 400/I-85 interchange. Check the latest news on weather and traffic.

Here’s what you need to know to navigate Atlanta on Sunday:

Bring an umbrella:

Early Sunday morning, there’s a 30 percent chance for a few showers and the thermometer should be in the low 50s, Channel 2 Action News meteorologist Brad Nitz said. The chance of rain climbs throughout the morning, however, and rain is likely by late morning and continuing through early afternoon. Temperatures will slowly climb through the 50s to reach to an early afternoon high of 61. Winds pick up in the afternoon to 15 mph, gusting to 25 mph from the northwest, Nitz said.

32,000 feet pounding the pavement:

More than 16,000 runners are expected for Sunday morning's Publix Georgia Marathon and Half-Marathon, which begins at 7 a.m. The races start and finish in Centennial Olympic Park, with the course running through many intown neighborhoods, including the Old Fourth Ward, Inman Park, Little 5 Points and Poncey-Highland. Runners will also pass by Agnes Scott College and traverse through Decatur, north Decatur and Druid Hills. Full or partial road closures will begin early Sunday morning and could last into the afternoon. If you want to check on traffic before heading out, you can do so at the WSB 24-hour Traffic Center. For the Publix Georgia Marathon and Half-Marathon course map, click here.

MARTA an early starter:

MARTA will begin rail service an hour earlier than usual Sunday morning (5 a.m.) in order to get runners and spectators to the starting line at Centennial Olympic Park.

For the scientifically inclined:

The first Atlanta Science Festival will continue Sunday at venues around the city. There are other events, both indoors and outdoors, to choose from as well. Full list of Sunday events.

Weekend construction roundup:

Interstate roadwork that began Friday evening will continue Sunday. The HOV and two adjacent lanes will be closed on I-85 southbound from just north of Clairmont Road to Ga. 400, and the HOV lane could remain closed through 5 a.m. Tuesday, as workers install a large overhead sign structure for the new Ga. 400/I-85 interchange, according to the Georgia Department of Transportation.

On the top-end Perimeter, three lanes of I-285 westbound will be closed nightly from New Northside Drive to Cobb Parkway, while in Douglas County, a couple of lanes in each direction on I-20 will be shut down nightly between Ga. 5 and Liberty Road.

But all those construction closings are weather-permitting, so there might not be any lanes closed. Click here for up-to-the-minute traffic reports.