Here in Charlotte, NC, I'm busy all year round. Obviously, spring is busy as it is in many areas, but I'm always crazy busy in summer and in November and December (when many people say they slow down).

Here in NH Spring is the best selling followed closely by fall. Things can slow in January and February depending on how bad a winter is, bad winter equals time on a Florida beach, a warm winter means lots of sales. 

We started June strong but the hot weather is slowing sales a bit. There will be another flurry in September and October.

In most areas of Florida February, March and April are busiest. That said many agents are busy year around!

January and February are typically our coldest months in terms of temps and activity. 

Cold, or hot; it makes no difference because in Florida, the weather changes rapidly

We outlawed seasons in California decades ago.  It's between 60 and 90, sunny 350 days a year.

we are lucky and have all 4 seasons that works.

it makes no difference here..... 

It doesn't make much of a difference in my market.  

The busiest time in Phoenix area is when school lets out so buyers get into new home before new school year starts.

No diff as of now as far as I can tell Ginger

Same here.

Some types of weather does affect the selling season.  Sometimes, the effect is simply the timing of the sales.