Thousands of homes narrowly escaped serious flooding as river levels came "within centimetres" of breaching defences in Manchester.
The Environment Agency said flood basins on the River Mersey in Didsbury came "very close" to being overwhelmed.
People evacuated from 2,000 homes overnight have been told they can return after river levels started to recede.
A major incident declared by Greater Manchester Police has been stood down.
"The latest update we have received has suggested that we are past the worst point of potential flooding," a spokesman said.
Earlier, Prime Minister Boris Johnson visited the overflow storage basin alongside the River Mersey in Manchester.
He thanked the Environment Agency for their "amazing preparations" and the effort to evacuate people overnight, but warned "there will be further rain overnight".
Didsbury and Northenden were among the worst-hit places overnight along with Little Bollington and Heatley in Cheshire and Maghull on Merseyside.
One resident, Rob Davies, said he and his family spent a worrying night after being forced to abandon their home in Didsbury.
"Waking up and not knowing what your house is going to be like in the morning is daunting," he said.
"We left our house last night and we were watching the river levels online. Luckily it didn't get as bad as predicted."
Lee Rawlinson, from the Environment Agency, told BBC Breakfast: "At Didsbury, the River Mersey got to very high levels very quickly, the water was pouring through there.
"The top of the river came within centimetres of the top of the riverbank but our defences there have served their purpose and kept those properties dry.
"But it was very close."
But Richard Kilpatrick, Lib Dem councillor for Didsbury West, said many people decided to stay in their homes and ignore the evacuation advice because they were scared about the virus.
"It was a major issue. It was also so hard to convince vulnerable residents to leave their homes when they've been told for so many months to stay home.
"It was fighting that anxiety of telling them that it wasn't safe to be at home," he said.
Downing Street has said Covid-secure facilities will be available for any people forced to evacuate as a result of the weather.
About 50 people, mainly from sheltered accommodation in Northenden, were evacuated to The Forum Leisure Centre in Wythenshawe, while others went to Didsbury Mosque.
Tracey Pook, who helps to run the mosque, said: "We wanted to open the doors to the community that we are here for, it's our duty.
"We've got volunteers on standby, waiting to help wherever they can."
Ann Stapleton-Amphlett, general manager of the Swan With Two Nicks pub in Little Bollington, Cheshire, said there had been "severe damage" inside the building.
"Thousands of pounds worth of stock is just floating around and bobbing around in the cellar," she said.
"On the back of all the upheaval with Covid, it just seems an ongoing nightmare."
At the scene
BBC Radio Manchester's Anna Jameson in Little Bollington
It's very cold and very wet at the moment.
The main road in Little Bollington, which leads on to the River Bollin and sits alongside the National Trust's Dunham Massey site, has essentially become a river, with water peaking at about 2ft (60cm).
Residents were asked in the early hours to evacuate because there was a danger to life and the same happened just downstream in the village of Heatley.
Some people who have been evacuated have had nowhere else to go, because of the Covid restrictions.
In Northenden, in south Manchester, people initially sought refuge at the Wythenshawe Forum where they were welcomed with biscuits, cakes and brews.
Many had come from sheltered housing and were elderly and vulnerable. Some were confused by what was happening. Thankfully, they have since been transferred to hotels.
The Greater Manchester Combined Authority believes river levels have finally peaked here, which is fantastic news for residents.
Greater Manchester Assistant Chief Constable Nick Bailey believes the water levels in parts of south Manchester were the highest ever recorded in the area.
Greater Manchester fire crews spent "an incredibly busy night" dealing with dozens of incidents and working with police officers visiting homes to warn residents.
A high volume pump was also brought in after floodwater threatened a road bridge in the Palatine Road area.
While river levels have now started to fall, severe flood warnings remain in place for the River Bollin at Little Bollington and Heatley, near Warburton, and also at the River Dee at Farndon.
On Merseyside, some residents in the Maghull area were also advised to leave their properties due to "unprecedented" water levels at Dover Brook near the River Alt.
The flood alert for Maghull has now been downgraded from "severe" but water levels are still high and some homes may still be at risk, said Sefton Council.
The Environment Agency said that while this was "good news", it expected water levels to remain high throughout the day with flooding to properties still possible.
Torrential rain turned into blizzard-like conditions late on Wednesday, causing additional problems.
BBC weather presenter Simon King said the situation was "unprecedented".
"It was about a month's worth of rainfall in 48 hours," he said. "There was a crazy situation where we saw snow falling.
"I don't think we have been in a situation where we have had severe flood warnings and snow settling as well."
The Met Office has issued a yellow warning, saying ice forming as the rain and snow clears could lead to difficult travel conditions.
Network Rail has advised passengers not to travel on many of its routes in the North West "due to increasingly poor conditions following torrential rain across the region".
Rail services have been cancelled between Liverpool, Manchester and Warrington, Northern warned.
Flooding is also affecting the rail replacement buses on part of the Merseyrail network.