"It's sunny today." - "..."
Don't forget your sun hat / Put on your sun hat.
What's the weather like?
It's windy.
"It's hot today." - "..."
Bring your water bottle / Don't forget your water bottle / (Don't forget to) drink a lot of water.
"It's snowing today." - "..."
Put on your scarf / Don't forget your scarf.
What's the weather like?
It's cold / freezing / snowing.
What's the weather like?
It's cloudy
What's the weather like?
It's sunny.
What's the weather like?
It's hot.
What's the weather like?
It's raining