At the start of combat, Forecaster champions grant adjacent allies different buffs depending on the current weather, which changes every game.
Sunny Weather:
Combat start: Grant a 400/600/4000 Health shield to adjacent allies for 10/10/45 seconds.
Windy Weather:
Combat start: grant bonus Attack Damage and Ability Power to adjacent allies, increasing by 15/25/150% every 5 seconds.
Rainy Weather:
At the start of combat, Forecaster champions grant adjacent allies 20 / 40 / 100 mana until they have cast 1/1/100 spells.
(1) ??? (Randomly selected per game)