All Pokemon except Ice types and those with the Ice Body or Snow Cloak abilities lose 1⁄16 of their max HP at the end of each turn.
Pokemon with the Ice Body ability recover 1⁄16 of their max HP each turn.
Pokemon with the Snow Cloak ability increase their evasion by 20%.
From Generation 4, Blizzard has 100% accuracy.
In Diamond/Pearl only, Blizzard has a 25% chance to break through Protect and Detect.
The move Weather Ball changes to Ice type and doubles in power.
The power of SolarBeam decreases by 50%.
The moves Synthesis, Morning Sun and Moonlight recover 1⁄4 of the user's max HP (instead of the usual 1⁄2 HP).
Castform changes to its Hail form.