This is the 1002nd most frequent Polish word.
zmianie
"Zmianie" means "change" (locative or dative case in Polish).
Here, 'zmianie' is the dative case of 'zmiana', used to indicate the indirect object of the change in question (the alteration of weather).
Na zmianie pogody czułem się nieco nieswojo.
The change in the weather made me feel slightly uncomfortable.
'Zmianie' is used in locative case of 'zmiana', indicating the topic of conversation ('about the change').
Rozmawialiśmy o zmianie podejścia do projektu.
We talked about changing the approach to the project.
In this sentence, 'zmianie' is the locative case, utilized to specify context ('at the change', in this scenario regarding the course alteration).