Weather
As far as the picture's concerned there are only two types of weather, snow and rain, and sometimes a little of each.
I tried drawing sleet, I really, really, tried, but it just ended up looking like malformed rain which I suppose is a fairly accurate characterization of sleet, but nevertheless looks pretty dumb in the picture.
And as for hail, don't even get me started about friggin hail.
Although, sadly, I only have two types of precipitation, this is made up for a bit in the fact that they come in three gloriuous intensities.
Light precipitation

A little rain speckling on your glasses, or some flurries that seem to disappear even before they hit the ground.
Medium precipitation

Cause for an umbrella in the case of rain or the celebration of school children in the case of snow.
Heavy precipitation

Holy crap! It's time to start building an ark...um, or diggin a tunnel...
and one extra permutation...
Lightning

Naturally, you can have thunderstorms as well, or even thundersnow.
The Moon
If I've done the math right the phase of the moon in the picture should match what you see. I started work on calculing moonrise, moonset times and elevation from the horizon
but there's big problems with that line. The picture represents less than 10 degrees of elevation and the maybe 100 degrees azimuth range across the horizon, so the moon would
only be visible in the narrow are the picture covers for a very short period of time if at all each day, and only rarely would it be framed nicely with the Empire State.
So, I decided to compromise accuracy for aesthetics.
The colors of the Empire State Building
The kind people at the ESB website are nice enough to keep their lighting schedule online. I'd love to just scrape it and toss it in the database, but
unfortunately it's all text fields and scraping ends up being a pretty decent pain. So, keeping that schedule up to date means regular data entry, which
could be nightmare, but thankfully my mom volunteered for the position. Everyday she checks the page, updates the colors and even adds a little tidbit
regarding the occasion that precipiated the color choice. Think thats cool? Check out her biting
commentary on alcohol, sex, film, and literature.
Try it out for yourself