Mortgage rates have soared since the start of the year, with the average two-year deal climbing from 4.83pc in early January to 5.93pc today, Moneyfacts figures showed.
Adam French, at Moneyfacts, said borrowers were facing “the most challenging mortgage market in modern records”.
He said: “Not only have rates been jumping up and down, but the deals available today may not be here tomorrow either.
“Previous events such as the mini-Budget and the Covid pandemic caused considerable disruption – but the prolonged nature of the volatility we have seen so far this year stands alone.”
Mr French added that mortgage rate volatility was beginning to harm consumer confidence, with those who had managed to lock in lower deals typically doing so thanks to “luck rather than judgement”.
The Bank of England is widely expected to raise rates from the current level of 3.75pc, with markets predicting an increase to 4.75 to 5pc by late 2027.