Temperatures in England on Saturday were higher than those in Athens, Los Angeles and Barcelona.
A record reading for October of 29.9C was set at 2.42pm BST in Gravesend, Kent.
The BBC reports the previous record of 29.4C was in March, Cambridgeshire, on 1 October, 1985.
In Wales, a new record was set at 28.2C in Hawarden, Flintshire, at 2.12pm BST.
In Edinburgh on Wednesday, the temperature was 24.7C - the warmest day in Scotland for the time of year for more than 50 years.