The idea is part of the Conservative Party manifesto for the Brighton and Hove City Council election on 7 May.
"The technology is there. It works in America, so why not in Brighton?" said Councillor Geoffrey Theobald.
The Greens and Lib Dems said the idea was bizarre and absurd, Labour said it was unclear and UKIP said it wanted to reduce residents' parking fees.
Parking on Brighton seafront costs up to Â£15 for a full day but the Conservatives said variable fees could be introduced in response to the weather forecast.
"Madeira Drive is a classic example, where it can be very wet and stormy," said Conservative group leader Mr Theobald.
"If you knew in advance, you could make your charges cheaper for people coming in.
"Car parks could work on this sort of idea as well."
Green Party spokesman Councillor Geoffrey Bowden said it was a mad scheme.
"I just don't see how it's going to work," he said.
"We have record numbers of people coming to Brighton. This is completely unnecessary."
Labour Councillor Gill Mitchell said: "It's just unclear how on earth this is going to work.
"Are the Tories going to introduce a variable tariff ranging from light drizzle to full-blown monsoon?"
UKIP Councillor Leigh Farrow said his party wanted to reduce parking costs for residents, who have to pay over Â£100 for permits.
"We think they should get reduced parking or free parking elsewhere for limited periods," he said.
"Residents are paying through the nose."
Liberal Democrat candidate Jeremy Gale said: "It is an absurd idea.
"It will be impossible to implement, difficult to manage and may even end up costing the council money via an appeals process.
"A far more sensible approach is to implement free Sunday parking across the city, regardless of weather conditions."
Parking fees should be reduced in bad weather to encourage visitors to Brighton, city councillors have said.