ScotRail's performance level is at its lowest since the franchise began, according to new figures.
They showed 81.8% of services arrived within five minutes of scheduled time between 16 September and 13 October.
ScotRail's moving annual average for punctuality also hit a franchise low of 87.5% - below the agreed breach level of 88.22%.
ScotRail said there had been "significant disruption" as a result of Storm Ali in September.
The rail operator, whose franchise began on 1 April 2015, was fined more than £2.2m for performance breaches in the first half of 2018.
The new performance figures came as a freedom of information request by Scottish Labour revealed that ScotRail's performance benchmarks were waived last month by Scottish Transport Secretary Michael Matheson until June 2019.
The waiver included the caveat that "any further drop-off in performance will be unacceptable".
Responding to the latest performance figures, a Transport Scotland spokeswoman said: "The significant increase in infrastructure issues not in ScotRail's direct control, many caused by severe weather including Storm Ali, clearly had an impact on performance.
"It is only fair to staff who braved difficult conditions to keep as many services going as possible that this is taken into account.
"However, as stated on many previous occasions, ministers expect the ScotRail Alliance to work closely together to build on lessons learned going forward, including those set out in the Donavan Review."
She added: "We should not lose sight of the transformational process under way on our railways, including the infrastructure enhancements, as well as the introduction of new and fully refurbished rolling stock with the additional services that they will provide, which should help deliver an improvement in overall performance moving forward."
Scottish Labour called for the reinstatement of franchise benchmarks and said the figures highlighted the need to bring Scotland's railways back into public ownership.
The party's transport spokesman Colin Smyth said: "These are shocking figures, but it is little wonder performance is plummeting after the SNP gave ScotRail a licence to fail until June next year.
"Far from being punished for their failings, ScotRail are being let off the hook."
ScotRail Alliance managing director Alex Hynes said staff at ScotRail and Network Rail had "worked flat out to keep people moving and to get services returned to normal as quickly as possible" following the arrival of Storm Ali last month.
He added: "We are investing billions in improved infrastructure and hundreds of millions of pounds on new and upgraded trains as we continue to do everything we can to improve performance.
"It's part of our plan to build the best railway Scotland has ever had."