In German are days and months written with capital letters?

Yes, in German, days of the week and months of the year are written with capital letters.

Examples:

* Montag (Monday)

* Dienstag (Tuesday)

* Januar (January)

* Februar (February)

This rule applies to all parts of the word, even when they are used in abbreviations:

* Mo (Monday)

* Di (Tuesday)

* Jan. (January)

* Febr. (February)

This is in contrast to English, where days and months are not capitalized unless they are part of a proper noun (e.g., "May Day").