Bear ScotlandScotland’s five-week stretch of dry weather will come to an end later with heavy rain, hail and thunder expected over the weekend.
Drivers in Argyll have been warned about potential landslides on the A83, with an alternate route to be opened as a precaution.
Environment agency Sepa has recorded water scarcity across the country after Scotland’s driest period in 60 years.
But it warned that the incoming rain, which is due from Friday night, is unlikely to be enough to replenish river levels.
It said that there would need to be “well above average rainfall” after the prolonged dry period.
Sepa also said there had been no rainfall in parts of Fife for more than a month and the east of Scotland was particularly dry.
And it said that if there was no significant rainfall over the next seven days, the River Esk in Dumfriesshire would be raised to “significant scarcity”.
In Argyll, the A83 at the Rest and Be Thankful is known for its potential for landslips.
Roads agency Bear Scotland is planning to open the Old Military Road alternative route as a precaution from 20:00 on Friday until Tuesday morning.
Euan Scott, Bear Scotland’s north west representative, said: “The safety of road users is a top priority and we closely monitor conditions at the Rest and Be Thankful on a daily basis.
“While the weather has been extremely dry and sunny in recent weeks, our decision to divert A83 traffic is based on the incoming forecast for heavy rain, and our experience of previous events where landslides have occurred during the first heavy rain after extended periods of dry weather.”
Transport ScotlandScotland has enjoyed dry weather for five weeks – the driest start to the year since 1964.
The hottest day of the year so far was 13 May, with temperatures of 25.5C recorded at both Tyndrum in Stirling and Auchincruive in South Ayrshire.
And this spring is so far currently ranking at the driest spring in more than a century, according to the Met Office.
Scotland’s senior weather presenter Christopher Blanchett said: “It’s not rained in parts of Scotland for five weeks thanks to a blocked weather pattern.
“High pressure has been dominant overhead keeping conditions dry and settled, compressing the air and allowing it to warm.
He added: “This weekend will see high pressure relinquish its grip, allowing the Atlantic to roar back to life and send weather systems our way from the west.
“We’ll see a spell of heavy rain on Friday night, followed by an unsettled spell through the weekend and into next week too.
“There will be frequent showers on Saturday and Sunday with hail and thunder, along with a spell of blustery westerly winds.”