system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are we able to determine things such as wind speeds and temperatures on planets outside of our solar system?
gpt
It's actually not determinations, but rather predictions based on environment. 


Everything on a planetary scale is very hard to judge. Since the objects are so small and doesn't have the aspects of stars. For example, we can easily predict a stats temperature based on luminosity and how it falls on the heat spectrum. Although, this isn't anything you can do over a night. But rather daily observations.


So now back to your question. Planets have different perks based on their conditions. Which can help to predict the climate. Also if you observe the host star you can also estimate distance and size based on passages. Because planetary passages block some of the sunlight, making the frequency unnatural. Larger planets have a larger passage when they pass in front of their stars compared to smaller ones. Not only that but the frequency of passages makes estimates for size and distance.


Now we let's touch on the atmosphere. Which works like a konvex lens and have properties for estimations. Which indicates what the planet can contain in terms of materia. And could show wind speed.


In concussion. It's estimations based on raw data and analysis. Some of the predictions are based on concussions drawn from the findings of coincidental factors based on our own solar system. But at the end of the day that's the best you can do with out current technology.