The warm weather is not expected to relent over the weekend with highs of 24C possible in south-east Wales and around the Bristol Channel on Saturday and Sunday.
Other areas around the UK can look forward to temperatures reaching high teens and early 20s.
Met Office forecaster Simon Partridge said the high temperatures for the bank holiday weekend were a rarity in how dry it was expected to be.
“We’re slowly getting there. Hints of summer,” Mr Partridge said. “For a bank holiday weekend it’s pretty rare to be that dry and sunny I guess, so we’re not doing too bad.”
Rain is unlikely to trouble the UK over the next few days, with Met Office deputy chief forecaster Steven Keates saying indications are that the dry, bright weather is likely to continue for most – with little in the way of rain throughout next week.
Forecasters say the hottest day is yet to come though, with temperatures expected to reach as high as 24C.
The highest temperature of 2023 was recorded in Cardiff on Monday at a balmy 23.4C.
Met Office chief forecaster Paul Gundersen said: “The jet stream sitting to the north of the UK is holding unsettled weather systems at bay and allowing high pressure to dominate, bringing fine weather to the vast majority of the UK.
“The current position of the high pressure means we will see a westerly air flow over the UK, a cooler direction than if air was being brought up from the south, and areas such as Spain or Africa.
“Therefore, we are not likely to reach heatwave conditions, but temperatures will still be warm, reaching the low 20s for many, particularly in the South West and southern Wales.”
A Met Office spokesman said that the pollen count for England and Wales was high as the country entered the grass pollen season and was expected to remain until the current hot spell breaks.
The spokesman added the pollen count for Scotland and Northern Ireland was moderate/low as these areas remain in the tree pollen season.
Meanwhile, travel experts are warning of a busy time on the roads.
RAC spokesman Rod Dennis said: “We fully expect families to make the most of the largely fine weather over the coming days which is we’re forecasting the busiest late May bank holiday since before the pandemic.
“Into next week and half term for many parts of the UK, day trips will also be a big feature with popular routes to the coasts and countryside becoming busy.
“Getting away early in the morning or delaying trips until the evening are the best way to avoid the inevitable delays.
“Ensuring oil and coolant levels are where they should be is a must, as is checking tyres are free of damage and are properly inflated.”
People are being advised to take care if they plan to cool off by swimming in rivers or lakes.
Mid and West Wales Fire and Rescue Service have warned that hazards include strong currents, water quality, uneven riverbanks and tombstoning without know the water depth or location of underwater objects
A spokesman said: “The idea of swimming in a river or lake will be appealing to many people during this current spell of warm weather.
“Around 85% of accidental drownings occur at open water sites, and many of these drownings occur due to a lack of knowledge and understanding of the hazards posed by open water.
“Whilst the benefits of open water swimming are well documented, we feel it’s important to remind potential swimmers of the hazards posed by swimming in open water.”