Given the sentence "Brunette girl with backpack readying a colorful kite." is it true that "Girl is outside on a windy day."?
A step-by-step solution is:
it is not possible to tell
Just because the brunette girl is readying a colorful kite it doesn't mean she is outside on a windy day.

She may be at her kitchen table readying the kite for adventures tomorrow.

.

Therefore, the answer is it is not possible to tell