Firefighter Phil McFarlane said watching the cat owners visit the cattery to see if their cat survived "has been difficult".
He added that they were working with the cattery owners to find how many cats were killed in the blaze.
More top news
Many places will stay dry with sunny spells, although isolated showers are possible, especially during the afternoon and evening.
A cloudy start, but sunny intervals developing from the west through the afternoon.
Police investigating missing Madeleine McCann have contacted Australian officials over the discovery of remains in a suitcase, the Met said.