Yellow weather warnings have been issued by the Met Office as much of Scotland faces heavy rain and strong gusts of wind up to 75mph, causing flooding and disruption.
Forecasters said that 20 to 30mm of rain is likely to accumulate in a matter of hours, with a chance of up to 40mm in one or two areas of the north.
Gusts of wind from 65 to 70mph are likely to batter coastal areas, with 75mph winds possible around the Northern Isles.
STV meteorologist Sean Batty said: “On Friday, Scotland sees its first proper blast of autumn with wind gusts the strongest we’ve seen since spring.
“A very active jet stream originating from just north of Hurricane Ian has intensified a low pressure system in the Atlantic and this is what brings us these autumnal conditions today.
“Winds will peak through the first half of the day with gusts of 70mph possible around the north coast and possibly 75mph around the Northern Isles.
“Along with the strong and gusty winds there will be heavy rain, although for a fairly short period of time, but this could still lead to flood issues on some roads in the west and central parts of the country.”
The rain is expected to clear to showers early by mid-afternoon, and the weather warnings are set to end by 3pm on Friday.
Travel is disrupted across the country as ScotRail have implemented speed restrictions which will last until Saturday morning.
A ScotRail spokesperson said: ”Due to adverse weather conditions, we have various blanket emergency speed restrictions implemented across our network today and early tomorrow (Saturday, 1) morning.
“Please check the app for the latest info.”
Almost all CalMac passenger ferries apart have one or more sailing disrupted, with several having cancelled the routes for the remainder of the day.
Meteorologists have said that road delays can also be expected as a result.
“We have the addition of the first proper leaf fall of the season and this can block drains and exacerbate localised issues on some of our roads,” Sean added, “Ferry disruption is likely, along with restrictions on some of the bridges.”
“Looking ahead to the weekend it is expected that “winds will remain very blustery on Saturday and lots of heavy showers will be blown across the country.
“The outlook for Sunday looks like “the best day of the weekend” Sean added, “But more wet and windy weather is on the way next week.”