Updated March 13 at 4:30 p.m.-- Today’s northeaster, which rolled into the Commonwealth in the wee hours of Tuesday morning, could be the biggest the city has seen since the record breaking winter of 2015, Mayor Martin Walsh warned.

Walsh said, unlike recent storms, there are no severe high tides in store – but the the city is ready for a major weather event. Forecasters say the storm could bring 18 inches of snow to Boston by the time it clears out late Tuesday or early Wednesday.

“It feels like we haven’t really seen this type of storm since 2015, we’ve had storms in 16 and 17 and a couple this year, but it seems like this is going to be a big one,” he said. “We’re getting ready for it and taking this one very seriously.”

About 9 inches had fallen by 4 p.m., the mayor said in a press conference. There were limited power outages, but the primary concern was snow removal, he said. Three trees were downed in this storm.

A series of consecutive blizzards broke snowfall records in Boston during the winter of ‘15. Looking ahead, Walsh warned that this storm could be followed by another and urged residence to prepare.

“After the storm winds down, temperatures are going to remain low," he said. "We won’t see much melting this week so a lot of this snow will be on the streets for at least a week. And we’re looking at a potential ‘nother storm coming in sometime next week, so try to do your best to get down to pavement when you’re shoveling.”

Walsh said 800 pieces of equipment were clearing snow – and he urged residents to call 311 with any concerns about snow plowing or removal.

“Just be patient, we will get to you. We’re putting on extra additional staff, and we’ll have additional staff on Wednesday as well, taking any calls you might have... and I promise you we will get to your streets and plow your streets.”

Schools and libraries are closed, as the mayor directed all non-emergency city personnel to stay home. All Boston Centers for Youth & Families (BCYF) community centers are closed. Schools would also be closed on Wednesday, he said.

The Massachusetts Department of Transportation announced Monday that the HOV lane on I-93 would be closed. Commuter rails are operating on “extremely reduced schedules,” and MBTA subways are running on reduced frequencies. The Mattapan trolley is replaced by shuttle buses and MBTA ferry service has been suspended.

A city Snow Emergency and Parking Ban went into effect on main roads beginning at 7 p.m. Monday, and towing began at 10 p.m.

Those parking in all city neighborhoods but the South End will be allowed to use space savers for 48 hours from when the snow emergency ends. Residents have three hours after the storm ends to shovel their walkways, Walsh said.

National Grid said they were seeing an “increase in outages due to the blizzard, bringing down wires and equipment,” and Eversource reported 185 outages in Boston at just past 11 a.m.

A sign of the storm’s severity -- with vicious wind chills compounding the snowfall -- the Eire Pub is closed for the day, though the Banshee remains a winter weather stalwart and will be open. Savin Hill staple McKenna’s Cafe is also open, as Upham’s House pizzeria and Ba Le on Dorchester Avenue for the neighborhood’s pressing Bahn Mi and Vietnamese coffee needs.

And for the beer-happy, Dorchester Brewing Company will be open from 11:30 a.m. to 11 p.m., tweeting “we’re embracing the snow.”

But no movie day out for Dorchester today -- the AMC in South Bay is closed.

The St. Patrick's Day parade faces an uncertain fate, Walsh said Tuesday afternoon. "We'll play it by ear," he said, citing concern about timely snow removal as a factor.