What does the idiom "a ray of sunshine" mean?

If someone says, "It’s a scorcher today," what are they talking about?

If someone is "walking on sunshine," how are they feeling?

If someone is "in the dog days of summer," what does that mean?

They are experiencing the hottest days of summer

What does the expression "full of hot air" imply about a person?

What does the idiom "summer fling" refer to?

A brief romantic relationship during the summer

What does "make hay while the sun shines" mean?

Take advantage of a good opportunity while it lasts