The new high beat the previous record of 20.8C set in central London on March 23 and at Treknow in Cornwall on March 25.
Amid the record temperatures, Easter holiday destinations like Majorca, Ibiza and Greece will only have highs of between 16C and 20C.
Although today is expected to be slightly cooler, temperatures are still expected to reach 23C for sunbathers and staycationers in parts of southern and central England.
The weather is expected to be dry with temperatures rising to 23C in the West Midlands and eastern Wales, while the northern, central and south eastern parts of England are predicted to see highs of 20C (68F).
It comes as millions of drivers took to the roads at the start of a long weekend desperate to make the most of the Bank Holiday sunshine – with an estimated 22.48million journeys taking places over the four days.
A person surfs along the glistening waters at Porthmeor beach during the hot weather on Easter bank holiday weekend in St Ives
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A person surfs along the glistening waters at Porthmeor beach during the hot weather on Easter bank holiday weekend in St Ives
Colourful surfboards are out at Porthmeor beach in St Ives as people hit the waves to make the most of the warm, sunny spells today
Colourful surfboards are out at Porthmeor beach in St Ives as people hit the waves to make the most of the warm, sunny spells today
People enjoying the warm the weather in St Ives as they soak up the sun, build sandcastles and play volleyball at Porthmeor beach today
People enjoying the warm the weather in St Ives as they soak up the sun, build sandcastles and play volleyball at Porthmeor beach today