Met office has warned.
«As we go through the week, the high pressure tends to drift further eastwards; we could waft up some warmer air — some significantly warmer air — by the time we get to Friday and in to Saturday,» Met Office forecaster Alex Deakin said.
London, the national capital, is expected to approach the mid-20s on Saturday and Sunday.
Manchester, Birmingham and Cardiff may experience temperatures in low 20s.
In Belfast and Glasgow, Met Office has forecasted temperatures of 21C and 19C respectively
The latest forecast comes month after the Met Office provisionally called September the UK's joint warmest on record.
For UK, October started on a high with 24.1C temperature recorded at Wisley in Surrey on Sunday.
Last month, UK experienced seven consecutive days with temperatures above 30C- the highest ever in the country's history recorded by the Met Office.