The temperature gauge peaked at 25.2C in the north-west Highlands this afternoon.
The reading was recorded at the Met Office observation station at Achnagart, situated north-west of Fort William.
Scotland’s previous hottest day of the year was recorded over the Easter weekend on 20 April when the temperature climbed to 24.8C at Floors Castle in the Borders.
Scotland was warmer today than Paris, Berlin, Rome, Amsterdam and Athens, BBC Scotland weather presenter Christopher Blanchett confirmed.
Edinburgh peaked at 21C, while Glasgow sizzled at a high of 23C reached around 3pm.
The UK was basking in sizzling sunshine, with the mercury edging to 25.8C at Treknow in Cornwall.
Temperatures in the mid-20s are said to be unusual for this time of year.
Met Office forecaster Greg Dewhurst said it looked like Wednesday would be the warmest day of the week, adding: “Tomorrow there’ll be a little bit more cloud around generally across the UK.
“It should be mostly dry but there is the risk of one or two showers for western parts of Scotland, perhaps Northern Ireland, but most places will be dry with still some sunny spells.
“We’re probably looking at maximum temperatures tomorrow around about 20C, maybe 21C, so just coming down a little bit.”
The forecaster said that during the past eight out of nine years, about 20 per cent of May days in the UK have seen a maximum of 20C or higher.
“So it’s fairly unusual,” he said.
Mr Dewhurst said temperatures at the weekend could reach 20C or 21C and will not be as sunny.