Glasgow Central passengers hit by hot weather faults
All trains between Glasgow Central and Paisley Gilmour Street - the country's second busiest line - were halted during the afternoon rush hour.
It affected services to Ayr, Largs, Ardrossan, Gourock and Wemyss Bay.
Network Rail said three sets of points which connect tracks near the station had been affected by the heat, preventing trains from entering or leaving the station.
Temperatures hit 28C in the city today, and 31.3C at Aviemore in the Highlands - just 1.6C below the Scottish record set in the Borders in August 2003.
A further points problem on the Glasgow-Kilmarnock line near Stewarton halted trains on that route too.
There was also a signalling fault in Cumbernauld, stopping trains there as well.
A Network Rail spokeswoman said of the Glasgow Central disruption: "It is believed to be because of the hot weather."
A ScotRail Alliance spokesperson said: “We share customers frustration when these things happen, and we are doing all we can to reinstate services as soon as the signalling faults are resolved.
“Customers can keep up to date with the latest information on social media, on our website and mobile app.
"To keep people moving, we’ve arranged for train tickets to be used on local bus services.
“Anyone delayed by 30 minutes or more is entitled to compensation under our Delay Repay Guarantee.
"To claim, simply keep hold of your ticket and visit our website or mobile app.”