Calling a personal snow day, despite clear weather and no snow on the ground, on account of being lazy. Often used in college after a night of drinking, one declares a snow day followed by skipping all classes/meetings to play video games. Snow days may even be called for summer classes. Originating from Western Illinois University, Washington Hall 7.

That day everyone hopes for during the winter.

(noun) any day when school is cancelled unexpectedly, but not necessarily because of snow.
other causes include but are not limited to:
ice (bad roads), low temperature (buses can't start), winds, power outages, no heat, lice epidemic (school closes for cleaning), sickness (so many students are out sick that it's not worth keeping the school open).

the canadian version of a green day.

The act of waking your partner up by screaming, "SNOW DAY!" and proceed by ejaculating in his/her face.

After a long day of school, going home on a cold winter evening, and going straight to sleep, we wake up, to see the holy rays of light right on our bed, as they guide us towards the window, where it's a snow wonderland. Quickly, we turn on the TV, and watch the news broadcast, as our school is suddenly closed. In great joy, we don't have to worry about the PTSD that we're given. It's a blessing from god himself, for the loyalty of those who have survived school without committing suicide or running away.

The idea of the snow day itself is basically when you've reached nirvana temporarily.

When a man ejaculates into his pants, and has to take the day off to go home and change.