The prime minister will chair a meeting of the government's emergency committee later as parts of the UK deal with the aftermath of severe flooding.
Several parts of Yorkshire and the East Midlands were hit by a month's-worth of rain in just one day late last week, with areas around the River Don near Doncaster among the worst affected.
Around half of the 700 residents of Fishlake, near Doncaster, fled their flooded village and in Derbyshire a former high sheriff Annie Hall died after she was swept away by flood water in Darley Dale, near Matlock.
The Cobra (Cabinet Office Briefing Rooms) meeting comes despite Mr Johnson saying on Saturday that the situation "is not looking like something we need to escalate to the level of a national emergency".
At the time he had said: "You've got to face the reality that places like this are vulnerable to flooding – we're going to see more of it."
But Labour Party leader Jeremy Corbyn wrote a letter to the PM accusing him of not doing enough to help those in flooded areas.
He said: "If this had happened in Surrey, not Yorkshire or the East Midlands, it seems far more likely that a national emergency would have been declared."
The meeting is due to take place on Tuesday afternoon, as the rain is forecast to move to the south.
Helen Roberts, a meteorologist for the Met Office, said the outlook for parts of the country affected by flooding was "improving", although there could still be more heavy rain on Tuesday morning.