Ah, the weather. In our world, it is ever changing throughout every part of the world. In this little piece of America called Central Pennsylvania, it changes at essentially every blink of the eye. In a place like Hawaii, it hardly changes - staying consistent throughout the entire year.
But, enough about our world. What about the Avatar World? It seems like there's hardly any change, even as you move deeper into the Earth Kingdom. There's even a key inconsistency within the EK itself. I will be mostly focusing on climate at the time of ATLA, and mostly season one, as that is where I'd like to address some concerns about WoA weather. I might toss a passing mention to LoK time, but it is a bit more challenging since we only have mainly seen R-City so far.
So, when it comes to the first leg of Team Avatar's travels, we see some variations in the weather, and some odd inconsistencies. First thing we see of course is the arctic climate of the South Pole. Okay, no issues here - except of course that Aang is somehow managing to do okay down there (and later in the North) without a coat. Ummm, in an arctic climate in near-winter, how does he not get frostbite or something like that? That's a big issue right off the top there. There's no way he can survive down there with just that monk's clothing - heck, even with that robing he has in the finale! Sorry Aang, if you're going to live at the SWT in the future, get a coat. :p