iCal Holidays Spanning Multiple Days

Hey there, kat_bird.

Welcome to the Apple Support Communities! Sounds like you're running into some issues with Calendar on your Mac where it relates to certain events. Let's see what we can come up with together.

Do you have a single internet account that provides calendar info, or do you have several? You can check that in Calendar > Preferences > Accounts. If you do have more than one, it could be causing a potential conflict, but before any changes are made, let's just note whether or not more than one account is present. Also, let's make sure that your Mac is fully updated. To do that, follow the steps in How to update the software on your Mac. Backing up your Mac prior to updates is recommended, and the best steps to follow for that can be found in Back up your Mac.

Also, go ahead and verify that the date and time are correct on your Mac. This likely isn't the issue, but it's always good idea to verify that this is showing up correctly. Look over the "Check Date & Time preferences" section of If the date or time is wrong on your Mac for steps for that.

Thanks!

Hi kat_bird,

It still might be account related, as accounts can affect each other in this manner. Do you have the exact same accounts in Calendar on your Mac that you do with your iPhone and iPad? How about if you check the Calendar section of the iCloud webpage? Do the incorrect dates show there as well or are they aligned with how they appear on your iPhone and iPad?

Thanks!