CHICAGO (STMW) – City officials said “millions” of spectators are expected to gather along the lakefront for this weekend’s Air and Water Show.

The annual weekend show, which begins at 10 a.m. and ends at 3 p.m. on Saturday and Sunday, features the U.S. Navy Blue Angels, who will perform aerial tricks in their F/A-18 Hornets.

A clear blue sky greeted crowds on Saturday morning as temperatures hovered in the upper 60s, but scattered showers could hit the city on Sunday, according to the National Weather Service’s Chicago office. The weather agency forecasts a 40 percent chance of rain on Sunday at 1 p.m.

The head city’s Office of Emergency Management and Communications said the agency, which oversees the 911 call center, will be closely monitoring the annual event.

“As millions of people gather along Chicago’s lakefront to enjoy the festivities this weekend, it is important that they stay aware of their surroundings and prepare for any possible change in weather conditions,” said OEMC Executive Director Gary W. Schenkel. “As it does for every large-scale event, our operations center will work closely monitor the festival to ensure the safety of the public.”

A spokesman for the Chicago Police Department said no traffic accidents or other incidents related to the Air and Water Show had been reported Saturday morning.

The Chicago Transit Authority will increase service on various train lines during the event.

Trains running on the Blue, Brown, Red and Orange lines will include more cars before and after the annual show that takes place Saturday and Sunday from 10 a.m. to 3 p.m., the transit agency said in a statement, which added that more buses will be deployed along the lakefront.

The CTA said it urges commuters to leave early and allow for extra travel time.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2012. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)