The mysterious whistling sound on high turned eerie when the source proved to be the hurricane’s winds gusting through the exposed steel of the nearly complete Freedom Tower at ground zero.

And with that noise came a conscious thought that had until then been a jangling edginess whose own source was not immediately clear.

The thought was this: could it possibly be that 10/29 proves to be in any sense the meteorological equivalent of 9/11? Would disaster strike us again?

The anxiety increased as the storm drew closer and the city approached the hour that Mayor Michael Bloomberg warned would be the worst.

An added feeling of being trapped came as the closures were extended from the subway to the bridges and tunnels, and people were advised to stay inside. Where we had once stood spellbound by the sight of the burning towers, we now listened to the unholy roar of the wind. Windows and doors rattled, and sirens wailed in the gathering night.

Only this time the sirens were not converging toward one place. They were going in all directions, and to hear them was to imagine dire emergencies of every kind, everywhere.

If 9/11 was about what we saw, then 10/29 was about what we heard. And even when we cannot fully believe what our eyes behold, they are far better than our ears at gauging the true magnitude of a threat.

Hearing can tell us that something is getting closer and that it is awesomely big and getting bigger, but it cannot tell us exactly how frightened we should be.

Is that wind just noise, or could it tear off the roof, or maybe send something crashing through the window, or drive the water of the harbor up over the floodwalls? Was that last gust as loud as it could get? What was that loud bang? That crash? Is that why yet another siren has begun to wail? Are those two other sirens going there also? No, wait, they’re going the other way. Something else must have happened. But what?

All that was certain was that New York’s firefighters and cops and paramedics would do everything they could to help whoever needed them.

And the firefighters on 10/29 now included the sons of some of the greats of the FDNY who perished on 9/11. The fallen Fire Chief Ray Downey was the country’s leading expert on disaster response; two of his sons are now FDNY bosses. Chief Joe Downey commands New York’s Urban Search and Rescue team, which joined the rescue effort down south after Katrina. He and the rest of the department now faced a hurricane in their own city.

At the head of the city’s response was Bloomberg, who had been a long-shot candidate for the Republican nomination for mayor on the primary held on the same day as 9/11. He had begun that morning voting with a ballot on which he was making his very first appearance. He then walked downtown, and the chances of him ever becoming the mayor seemed ludicrously remote. Nary a passerby recognized him, save a woman he happened to know.

“I didn’t see you at the dinner party last night,” the woman said.

“Another dinner party I wasn’t invited to,” Bloomberg replied.

Not an hour later, the first plane hit the World Trade Center. One consequence of the attack was Bloomberg’s election. He never seemed more suited to be mayor than he did as this other, natural calamity known as Hurricane Sandy struck.

Bloomberg gave a briefing as the worst of the storm neared, and he was the personification of reasoned calm. He no doubt would have been so even if there had been mass causalities, but at that point it seemed there were reports of at most one fatality. There would be another report of two young boys killed by a falling tree, but it became clear that whatever the eventual tally, 10/29 was not going to be a tragedy of the numerical magnitude of 9/11.

This is still a disaster to remember, and the anxiousness at its approach was not only mass PTSD from the September morning when nearly 3,000 perished. Significant areas of Manhattan were flooded. Tunnels were filling with four feet of water or more. A fire unit radioed that it was in a rubber boat with a police emergency service unit seeking to determine if somebody was trapped inside an underground garage.

“There is water to the roof,” the firefighter said. “We don’t know if there’s a victim there or not.”

Another firefighter radioed a message that sounded like New York in the wake of Sandy was becoming for at least the moment too much like New Orleans after Katrina.

“The East River is coming over the wall!”

The river was rushing into a large apartment complex called Stuyvesant Town through Capt. Patrick Brown Walk, named after a former resident who died with his entire company in the North Tower. His physician brother, Mike, had been in one of the FEMA medical teams that responded to the Katrina disaster, and now cars were floating below what had been Patrick’s window.

But the city was not unraveling in the face of Sandy as New Orleans had in the face of Katrina. Bloomberg made that clear in a 10 p.m. press conference. He noted that the worst of the storm had passed, and the accompanying record surge would abate with the tide. Much of the water would drain away, and the rest would be pumped out as quickly as resources allowed.

“Things have gotten tough, but we’re going to get through this together as the city always does,” he said.

The storm surge had forced Con Ed to cut the power in lower Manhattan, and failing generators were causing New York University Hospital to be evacuated. The generators apparently fared better at the 9/11 Memorial, where the lights continued to shine through the tempest-tossed darkness.

The whistling through the steel also continued from on high, but now it was clear it should not have seemed eerie at all. The whistling was really saying we should not be so fearful, that whatever our eyes might see or our ears might hear, we should be steadied by what is in our hearts. We rose again after 9/11, so we certainly should not quake before some storm.

And however loud those winds roared around us, the sirens should have reminded us that we still have our spirit, on 10/29 or any other day, no matter what.

As Captain Brown of Stuyvesant Town said when somebody told him not to go up into the burning North Tower where so many people needed help, “What, are you nuts?”