Tell us about yourself!
Raspberry Pi Beer Fridge of Awesomeness
Then put your Pi + sense HAT outside and voila, you are detecting "weather" Mr. Dictionary Police.
Not true. You are using a sense HAT on a Pi to detect indoor weather (temperature, humidity, pressure). You are pulling outdoor weather data off of another site, but that is to compare with the indoor data that your sensors are collecting.
That error usually happens if you don't have a valid STATE or CITY parameter set. What are your STATE and CITY parameters set to?
Build a Raspberry Pi SUPER Weather Station