The tempest was threatening the Azores yesterday before racing north to batter the south coast and then rage up the Irish Sea.
The Scottish Environment Protection Agency said officials are monitoring the situation over fears that heavy rain could add to snow melt, sparking flooding.
Winds of this speed have previously caused chaos on the roads, especially on major bridges where crossing is deemed unsafe.
Last night, ferry operator Caledonian MacBrayne placed passengers on standby for delays and cancellations on many west coast routes as early as Tuesday (26 November). The company said it had received a forecast of winds hitting 61mph.
Most at risk are sailings from Ardrossan, Oban and Mallaig.
This will be the fourth ‘named’ storm of the season. It was christened by the Portuguese weather service due to its activity in the South Atlantic.
But the Met Office say it would probably have been given a name under its own warning system anyway, if the Portuguese had not named it first.
Forecaster Nicky Maxey said:”We are seeing strong winds coming through on Wednesday. There will be unsettled conditions in the south and south west.
“Gusts of 60mph can be anticipated, with 70mph possible in more exposed locations.
“The wind will be accompanied by spells of very heavy rain, with 50mm (two inches) in certain spots.
“Once Diana has moved through, a new low pressure system is coming in from the west on Thursday.
“Strong winds and heavy rain will continue to affect Scotland on Thursday morning, as this low pressure system passes over northern Scotland. It will remain blustery on Friday morning.”
The first yellow ‘be aware’ warning for wind starts at 9am on Wednesday for Central, Tayside, Fife, south west Scotland, Lothian and Borders and Strathclyde and lasts until 9pm.
Areas including Central, Tayside, Fife and Grampian are under a warning for heavy rain, from 12 noon until 11pm.
And the final wind warning affects the same regions from mid-day Wednesday until 3am on Thursday.
Temperatures will climb to an unseasonable 12C (54F) during Diana, due to the winds associated with the storm.
THREE DAY FORECAST:
Tuesday: Calm before storm. Dry start, followed by rain in the afternoon. Max 8C (46F) Min 3C (37F)
Wednesday: Storm Diana bringing high winds and heavy rain. Max 12C (54F) Min 7C (44F)
Thursday: New low pressure system arrives from west. Wet and windy. Max 12C (54F) Min 5C ((41F)