The word for Monday in Russian is понедельник. First a bit of history. The verb "to do" is делать. "To not do" thus is «не делать», and in ancient Russian one of the words for Sunday was неделя "the day on which you do nothing". The preposition по means after, and the suffix -ник forms a noun, thus the word понедельник means "the day after Sunday." Cool, huh? Of course nowadays nobody thinks about that history when they say понедельник. They just think of the first day of the week.

Some Americans say things like "I hate Mondays." The most common phrase about Monday in Russian is «Понедельник — день тяжёлый» "Monday is a tough day."

Though it is easy to memorize the days of the week in Russian, English speakers will need to keep in mind the prepositions that are used with them. If you want to say that something happened (or will happen) on a particular Monday, then you want the preposition в followed by the accusative case:

If you go there every Monday, then you want the preposition по followed by the dative plural:

If something started on Monday and is still continuing, you want the preposition с followed by the genitive case:

And if you want to give a range of days over which something will happen, for the starting day you use с + genitive and for the ending day you use the preposition по + accusative:

Last but not least, of course, you use the word in the nominative case when answering what day of the week it is:

¹ Some of my native speaker informants prefer the preposition до + genitive in this context along with the adverb включительно inclusively. Thus:

The Russian phrase for "season" in the sense of the time of year is «время года», literally "time of year," and the plural is «времена года» "times of year." There is also a borrowed word сезон with plural сезоны which means the same thing:

If you want to specify that something happens during a season, then you use the preposition в followed by the accusative case:

Note that if you use the names of the seasons—весна, лето, осень, зима—then those seasons go into the instrumental case when you mean "during that particular season":

One last quirk of the seasons is their starting date. In the States we say that winter starts on December 21st or 22nd. In Russia all the seasons start on the first of the month, so winter starts on the 1st of December.

We previously discussed the word ночь, which means night in the sense of the time between midnight and roughly fourin the morning. To say something happens during that period, you put ночь into the instrumental case.

Since in English we usually call that period of time “early morning,” that leads to some curious translations. Notice how «поздно ночью», which literally means “late at night,” is best translated as “early in the morning”:

The other day we discussed the usage of число to mean date in the sense of the first of the month, the second, etc. That's pretty straight-forward as far as discussing today/tomorrow/yesterday's date is concerned. But if you want to talk about the date on which something takes place, that's trickier. In that context the date goes into the genitive case, and despite the use of ‘on’ in an English context, no preposition is used in Russian:

In Russian if you want to clarify the date on which something occurs, you can ask the question «Какого числа?» For instance:

Although the «какого числа» question is perfectly grammatical, it's a bit more common to simply use когда. Both approaches are perfectly grammatical. I have the impression that Russian say «какого числа» more frequently than English speakers say “on what date”:

In English we say things like “Christmas is December 25th.” In Russian you always put the date in the genitive, you never leave it simply in the nominative:

For the sake of thoroughness, here is a sample sentence with all thirty-one dates:

The other day we discussed how to say things like “Today is the first.” Sometimes we want to include the month as well, and in Russian when we do that, the month must be put in the genitive case, but the date itself stays in the nominative:

Putting the month in the genitive is tricky at first because some of the months are end-stressed nouns; that is, when you put them in an oblique case, the stress shifts to the first syllable of the grammatical ending:

A couple more examples: