Summer Timetable is Easter to end August, there is then an autumn (fall) timetable to end October, then the winter timetable.
There is almost no difference these days between Summer and Fall timetables, and the vast majority of buses run all year round. So the seasonal definition is subtle.
In the St Ives area the only seasonal service was the Lands End Coaster. That is no longer open top anyway and this year ran in a very modified form, which is a year round schedule. Mousehole last year had the Mouse and the seasonal Cat buses (a deliberate pun). This year the Cat didn't run, just the year round Mouse.
Download the winter county timetable book here- https://www.transportforcornwall.co.uk/services
I have to be 100% honest here. First Bus are withdrawing all their 14 remaining commercial routes in Cornwall from February 2026. All those routes will be replaced by Transport for Cornwall (TfC), but not on like for like timetables. Services which haul round merely fresh air and no passengers (like the evening 17 to Penzance) will be modified. Cornwall County Council and Transport for Cornwall are currently working flat out to determine what can and can't be run, with an announcement probably very early in the New Year.
Whether TfC can run them all commercially, or whether county council support is needed has to be decided.