Philadelphia's 248th annual St. Patrick's Day Parade will make its way down Market Street starting at noon Sunday, in a spectacle that is expected to bring out nearly 20,000 participants, who will dance, march, and perform for thousands of spectators lining the streets.

With little chance of precipitation, temperatures are expected to hover in the high 30s and low 40s when the parade kicks off. According to the parade's website, the parade will march — as it does every year — rain or sunshine.

Philadelphia's St. Patrick's Day Parade dates to 1771 — five years before the Declaration of Independence was signed. More than two centuries later, here's what you need to know about the time-honored tradition.

Where: This year's parade will begin near 16th Street and John F. Kennedy Boulevard and make its way to Market Street, heading east before turning south on Front Street. The parade turns east on Dock Street to Penn's Landing. The parade's route map also shows that the performing area is at Fifth and Market Streets, near Independence Mall.

When: The parade will begin at noon and will last until 3 p.m.

Will there be road closures? Yes. A lot of them.

From 5:30 a.m. until 4 p.m. Sunday:
  • Market Street is closed between Fifth and Sixth Streets.
From 9 a.m. until 3:30 p.m. Sunday:
  • John F. Kennedy Boulevard is closed between 15th and 20th Streets.
  • 15th through 20th Streets is closed between Market and Arch Streets.
Also closed, from 10 a.m. (or earlier, depending on traffic) until 3:30 p.m. Sunday:
  • North Penn Square between 15th and Juniper Streets.
  • East Penn Square between John F. Kennedy Boulevard and Market Street.
  • Market Street between East Penn Square and Front Street.
  • All cross streets on Market Street from 13th to Front Streets, and from Chestnut to Arch Streets.
  • Front Street between Market and Chestnut Streets.

Will there be parking restrictions? Yes. And the city warns that your car will be "relocated" if not moved during these hours.

“Temporary No Parking Zones” will be posted on the following streets from 5 a.m. until 3 p.m.  Sunday:
  • Fifth Street between Chestnut and Market.
  • Sixth Street between Chestnut and Race.
  • Race Street between Fifth and Sixth.
“Temporary No Parking” zones will be posted on the following streets from 6 a.m. until 3 p.m. Sunday:
  • 1500-2000 block of John F. Kennedy Boulevard.

How about public transportation? SEPTA Bus Routes 2, 4, 5, 16, 17, 21, 23, 42, 45, 27, 31, 32, 33, 38, 44, 47, 47M, 48, 57, 61, 124, and 125 will be detoured from their normal routes through Center City and Old City from 7:30 a.m. until 5 p.m. Sunday. Detours will be posted and route changes are available on the System Status Page at www.septa.org.

Also, the city says to avoid bringing bags, backpacks, or satchels if coming by SEPTA's Regional Rail. All bags are subject to search. And no cups or liquids will be allowed on the Regional Rail.

Meanwhile, PATCO is already operating on an adjusted schedule for the Philadelphia Flower Show.

Are there certain things I can't bring in? Definitely. No weapons or contraband — even if you have a right-to-carry permit. No fireworks or explosives. No illegal substances or alcoholic beverages. No skateboards, motorized vehicles, or scooters (motorized wheelchairs, however, are permitted). No drones of any kind. And leave your laser pointers at home.

Do not leave bags unattended. And report any suspicious bags that you see.

I don't like the cold. Can I still watch? Of course. The parade will air live on Fox 29 in Philadelphia from noon until 3 p.m. It will also replay again on March 17, from 1 until 4 p.m., the mayor's office said Thursday.

Anything else I should know? A few things. It's daylight saving time, so make sure your clocks are set correctly. And if you are interested in extending the parade festivities, there will be a commemorative parade Mass in St. Patrick's Church near Rittenhouse Square, starting at 9:15 a.m. (Arrive before 9 for a seat.) The theme of this year's parade is "St. Patrick, bless those who respond to the call of the needy."

This year's parade grand marshal will be Sister Mary Scullion, the cofounder and executive director of Project HOME, the homeless outreach organization.