Learn Hardcore Russian: Дождь идёт.

Дождь means rain, and идёт is the third-person singular form of the verb идти, which literally means goes or is going. Even though the literal translation is "Rain goes", the expression is idiomatic in Russian—it conveys that it is raining.

Why is the verb идёт used in this weather expression instead of a verb that literally means "to fall"?

In Russian, weather expressions often rely on idiomatic usage. Although one might expect a verb like падать (to fall) to describe rain, the language traditionally uses идти to indicate an ongoing process. Thus, Дождь идёт naturally expresses that the rain is occurring right now.

What grammatical role does Дождь play in the sentence?

Дождь is the subject of the sentence. As a masculine noun in the nominative case, it clearly identifies what is happening—specifically, that rain is the element performing the action expressed by the verb.

Which tense and aspect is the verb идёт in, and why is that significant?

идёт is in the present tense and is in its imperfective aspect. This form is used in Russian to denote actions that are ongoing or in progress, which fits perfectly with describing a current weather condition like rain.