Иногда вечером я забываю отключать телефон.

Sometimes in the evening I forget to turn off my phone.

Breakdown of Иногда вечером я забываю отключать телефон.

• я: I
• телефон: the phone
• вечером: in the evening
• иногда: sometimes

Questions & Answers about Иногда вечером я забываю отключать телефон.

Why is it вечером and not в вечер for “in the evening”?

In Russian, parts of the day are usually used in the instrumental case without a preposition to mean “in the …” (time of day):

• утром – in the morning
• днём – in / during the day
• вечером – in the evening
• ночью – at night

So вечером is the instrumental singular of вечер, and it functions adverbially: “in the evening”.

В вечер is normally not used for time of day in modern Russian. You might see в этот вечер (on this evening) or в тот вечер (that evening), but that’s with a demonstrative word, not bare вечер.

Do we really need both иногда and вечером? Don’t they both mean something about time?