Scotland will go from flood to Factor 50 within just a few days this week.
What could start out as one of the wettest days of the year, this week could also finish the hottest.
Monday sees the country on yellow alert for torrential summer downpours, which could cause widespread flooding across Scotland.
As much as four inches of rain is forecast for higher ground, with half that at lower levels.
Yet by Thursday, Glasgow could be one of the hottest spots in the UK, basking in 25C (77F) heat.
By Friday, it’s School’s Out for Summer as the Mercury rises to 26C (79F) on the last day of term for many kids.
Glastonbury revellers could bake in 33C (91F) heat by Saturday.
The Met Office say homes and businesses could be inundated by floodwater and say some communities could become cut off.
The Met Office warning period began at midnight last night and extends right up to midnight tonight. Only the far west of Scotland has been excluded from the warning area.
The Met Office said:” There is a small chance that fast flowing or deep floodwater could suddenly occur, bringing a danger to life and extensive flooding of homes and businesses
“There is a slight chance of damage to buildings / structures from lightning strikes, hail, or strong winds
“If flooding occurs, road closures are likely, with long delays and cancellations to bus and rail services are possible
“There is small chance that spray, sudden flooding, standing water and/or hail will result in rapidly changing, dangerous driving conditions
“There is a slight chance power and other essential services, such as gas, water or mobile phone service will be lost.”
The Met Office also warn there is a small chance communities may be cut off.
But after a dreadful day today, Scotland dries up this week and we get to experience the benefits of a ‘Saharan bubble’ as warm air is drawn up from North Africa.
Forecaster Simon Partridge said the week will display a huge difference in prevailing weather conditions.
He added:”What a contrast we will see in Scotland’s weather over the next week.
“From a very wet start, things will brighten up brilliantly by the end of the week.
“The hottest day we have seen in Scotland so far was 25C (78F) at Kinlochewe in in Wester Ross on May 15. If our predictions are right, a new record could be established by Friday.”
Environment watchdogs SEPA have yet to issue any flood warnings for today but this is expected to change overnight and into this morning.
Yesterday, 'heavy rain forecast' warnings signs were flashed to drivers on Scotland's motorways.
Three day forecast:
Today: Thundery showers in east. Chance of sun in west. Max 18C (64F) Min 10C (50F)
Tuesday: Turning drier. Sunny in west but cloudy in east. Max 22C (72F) Min 9C (48F)
Wednesday: Mostly dry but cloudy in east. Sunny in west. Max 23C (73F) Min 9C (48F).