The Boston Pops Fireworks Spectacular, a tradition that has thrilled spectators on the Charles River Esplanade every Fourth of July for four decades, was rescheduled to be held a day earlier this year, on Thursday, to avoid a tropical storm that is expected to soak the region.
The change, announced at a press conference Wednesday, marked the first time since 1992 that the cherished fireworks and music extravaganza will be rescheduled.
“It’s not optimal,” State Police Colonel Timothy Alben said of the rescheduling. “We wish it were, but we’ve got to deal with this.”
With heavy rains caused by Tropical Storm Arthur expected to arrive by Thursday night, Alben left open the possibility that organizers would postpone the fireworks portion of the show until Saturday. However, he said the Pops concert would take place Thursday evening or not at all, due to “contracts and commitments” that some of the performing acts have.
“I’m not suggesting that we won’t cancel tomorrow [Thursday] if there is lightning concerns as we get further into the afternoon,” he said. “That’s a very real possibility.”
The National Weather Service said Wednesday that widespread showers and thunderstorms with locally heavy rainfall are expected to continue into Friday, as Arthur sweeps through the Atlantic, east of New England. The storm is expected to make its closest pass to the coast Friday night into Saturday.
Bad weather has caused trouble with the Esplanade celebration in past years, spoiling plans for the hundreds of thousands of spectators who come to mark the nation’s independence.
In 1992, the Boston Pops orchestra performed the concert, but the fireworks were pushed back a day because clouds hung so low over the city that visibility was limited.
In 2012, the concert and fireworks were delayed about a half-hour and crowds were evacuated from the Esplanade when a storm brought lightning to the area. The show was completed later that night.
During Wednesday’s press conference, officials said that Thursday appears to be the best day for this year’s festivities.
“Our teams have really been watching the forecasts and they don’t look great, and we think the best day to get the show in is tomorrow,” Department of Conservation and Recreation Commissioner Jack Murray said Wednesday.
“We’re keeping our fingers crossed that the weather cooperates tomorrow evening,” said Kurt N. Schwartz, undersecretary for homeland security and emergency management.
In an e-mail Wednesday to public safety officials around Massachusetts, State Fire Marshal Stephen D. Coan said fireworks mortars should not be loaded if heavy rainfall or high winds are forecast for show time. He said displays should be protected from rain, and fireworks should not be shot off during periods of high wind.
Festivities are scheduled to start at 8 p.m. Thursday, say State Police, and spectators will be allowed into secure areas beginning at 5 p.m. Storrow Drive will be closed at noon in both directions, and Memorial Drive will be closed at 6 p.m. on both sides, as will the Massachusetts Avenue and Longfellow bridges, State Police said.
Governor Deval Patrick’s office said he is set to join the Pops at the Hatch Shell on the Esplanade at 8 p.m. to narrate “This Difficult Song: The Star-Spangled Banner at 200.”
People visiting the city’s downtown area from out of state took the scheduling change for the Fourth festivities in stride on Wednesday.
“I don’t know that you can have fireworks in the rain, and of course the ambience isn’t as joyous,” said Vanessa Spallone, 41, of Orlando.
Gary Timm, 59, of Pierce, Neb., echoed those remarks. “You do what you’ve go to do,” he said.
Timm and his wife, Cheryl, 51, said they are pleased that organizers are being cautious with potentially dangerous weather ahead. They said the announcement gave visitors enough time to reconsider their plans.
“People are from out of town,” Cheryl Timm said. “They don’t know where to go if they have a problem.”
Frank Lawnicki, 46, of Chicago, planned to head to Cape Cod with family and friends on Friday. With the scheduling change, Lawnicki said, they will be able to attend the Esplanade activities.
“We’ll be down there watching the fireworks,” he said.
Councilor Josh Zakim, whose district includes the state-owned Esplanade, said he supports the scheduling change, in light of the adverse weather forecasts for Friday.
“The weather appears pretty foreboding,” Zakim said. “It’s disappointing. I certainly would prefer to celebrate the Fourth of July on the Fourth of July, but no one can control the weather.”
The forecast prompted a number of other communities to cancel plans for fireworks, including Gloucester, Barnstable, and Foxborough. In addition, several municipalities postponed fireworks until Saturday or Sunday, including Worcester, Marblehead, Lynn, and Lowell. Franklin postponed its holiday laser show until Saturday.
Mayor Martin J. Walsh’s office said Wednesday that officials are working to keep the public informed about changes to the planned festivities, adding that residents should follow @NotifyBoston for updates on Twitter.
Parking will be banned on a number of city streets Thursday beginning at 6 p.m. until the conclusion of the fireworks display, including Berkeley Street, from Beacon Street to Back Street; Clarendon Street, from Back Street to Beacon Street; Beacon Street, from Arlington Street to Massachusetts Avenue; and Berkeley Street, from Commonwealth Avenue to Back Street, city officials said.
The Massachusetts Bay Transportation Authority will run rush-hour levels of service after 2 p.m. Thursday, with a large number of trains running late into the night to accommodate postfireworks crowds, transit officials said. Extra commuter rail trains will also be used.
Revelers attending Boston Harborfest, another annual Independence Day celebration, worried Wednesday about the effect the weather may have on the holiday weekend.
Among the concerned visitors was Levy Cavalcante, 19, a Brazilian native in town for a monthlong language program.
“It’s very disappointing,” he said.
John R. Ellement, Martin Finucane, and Martine Powers of the Globe staff and Globe correspondents Rachel Riley and Kiera Blessing contributed to this report.