Nouns ending in e, like ice or breeze, drop the e and add y:

breeze	breezy
ice	icy

3-letter words that have a consonant-vowel-consonant combination double the second consonant before adding the sufix –y:

fog	foggy
mud	muddy
sun	sunny
mug	muggy

Other adjectives used for describing the temperature include:

Freezing

Icy

Cold

Cool

Warm

Hot