If you've read our "In a Nutshell" section, you know that "Winter" is part of a two-song sequence sung at the end of Love's Labour's Lost. Like many poem-songs in English, the meter of "Winter"—is wait for it—iambic tetrameter. Tetrameter is popular in songs because the lines are a little shorter than pentameters, but not as short as, say, trimeters, which sometimes can seem kind of childish. Just sayin'.
So what in the world are we talking about? Well, iambic tetrameter is very similar to iambic pentameter, except there are four ("tetra-" means four) iambs, instead of five ("pent-" means five). What's that? You forgot what an iamb is? That's just a beat made up of an unstressed syllable followed by a stressed syllable. If you hear one out loud (like "allow"), you'll hear a daDUM sound.
Now then, how about a few examples? Here's the poem's second line:
And Dick the shepherd blows his nail.
You should hear those four iambs together: daDUM daDUM daDUM daDUM. Well, that's easy enough. How about one more? We give you, line 6:
Then nightly sings the staring owl.
Every line in the poem is as simple as that, except for lines 7-8 and 16-17. Those four lines are written in a meter known as iambic dimeter (which is just a line with two iambs). This odd little change is really just a matter of editorial convenience, though. Some texts will print the lines as one, so that it reads "Tu-whit, to-who! A merry note," in which case you end up with a line of perfect iambic tetrameter.
In addition to the regular meter, there are a few other things to note about this chilly little poem. It rhymes, like lots of songs, and the rhyme scheme for each stanza is this: ABABCCDEF, where the letter stands for that line's end rhyme. This means the first four lines of each stanza rhyme every other line, the fifth and six lines of each stanza are a rhyming couplet, and the final three don't rhyme at all, not even a little. If we had to summarize this rhyme scheme in one word that word would be: variety. Think about it: we go from rhyming every other line (ABAB), to a couplet (CC), to no rhymes at all (DEF).
The variations of the rhyme scheme contrast with the constancy or sameness of the tetrameter (every line, four iambs, with no exceptions). The juxtaposition of formal difference or variety (the rhymes) alongside formal sameness (the tetrameter) does a pretty neat job of reinforcing what the poem says about winter, the season. During the winter, everything changes: water freezes, milk freezes, roads get all screwed up, people cough and interrupt sermons, etc., and yet, nothing changes. People still cook (greasy Joan is busy at her pot), they still go to church, they find a way to heat their home and throw a few apples into the ale while they're at it.