CMF is notorious for weather issues. It's location in the mountains is as already stated advantageous for skiers but the approach and departure to the airport is complex and airlines require approved crews to operate it.
Because the weather minima are so high here, it does result in more than the average level of days where weather is below limits. I have a vague recollection that Jet2 pulled out of CMF due to the levels of weather disruption being experienced there.
Finally ROC10, don't take FR24 as gospel at CMF - it is frequently wrong. There are for example Titan operations I have noted going in and out which are not listed at all which may be additions or have replaced the listed TUI ops but not been updated.