German months are all masculine nouns, which means each one takes the article "der" and is always capitalized. The first six months are Januar, Februar, März, April, Mai, and Juni. The second half of the year consists of Juli, August, September, Oktober, November, and Dezember. To say "in January" or in any other month, you use the contraction "im" (short for "in dem"), as in "Ich habe im Januar Geburtstag" (I have my birthday in January). One tricky pronunciation is März, which sounds like "mehrts."
The four seasons in German are der Frühling (spring), der Sommer (summer), der Herbst (autumn), and der Winter (winter), and like the months, all four are masculine. To say "in summer," you again use the contraction "im Sommer," for example, "Im Sommer gehe ich schwimmen" (In summer I go swimming). The same construction works for all four seasons: im Frühling, im Sommer, im Herbst, and im Winter, giving you a clean way to talk about when activities happen during the year.
German telling time has a few conventions that may surprise English speakers. To ask the time, you can say "Wie spät ist es?" (literally "How late is it?") or "Wie viel Uhr ist es?" For full hours, simply state the number followed by "Uhr," so 3:00 is "Es ist drei Uhr." A peculiarity is how half hours are expressed: 3:30 is "Es ist halb vier," literally "half four," meaning halfway to the next hour. For quarter past and quarter to, use "Viertel nach" and "Viertel vor," so 2:15 is "Viertel nach zwei" and 4:45 is "Viertel vor fünf." Other minutes past the hour use "nach" (after) and minutes before the hour use "vor" (before), as in "Es ist zwanzig nach sechs" for 6:20.