Non-Past Verb + こともある

The structure [non-past verb + こと {が/も} ある] can be used to express something like, "There are times when..." It is used to describe something that occurs occasionally. Using the particle も can imply that something else also occurs, or that the event described occurs alongside something else.

Note that this grammatical structure is very similar to [past verb + ことがある], which is used to express an experience that you may or may not have.

晩ご飯はたいてい家で食べますが、ときどき友達とレストランに行くこともあります。
I usually eat dinner at home, but sometimes I go to a restaurant with a friend.

文法の説明を読んでも分からないことがある。
There are times when I don't understand a grammar explanation even though I read it.

同じ日の沖縄と北海道の気温の差が摂氏４０以上になることもあります。
Sometimes on the same day in Okinawa and Hokkaido, there can be a temperature difference of over 40 degrees Celsius.

その他に関東地方とか関西地方のように使うこともあります。
In addition, there are times when it's used like "Kanto region" or "Kansai region."

Note that the last sentence is referring to the usage of 地方 in conjunction with other words, like the names of places. This is not a great sentence out of context, but I wanted to note it here since I finally understand it.