for sure. Usually gets really busy before sundance and lightens up in the summertime. However I have always been able to keep a gig going for the last 3 years or so (knock on wood). It just comes down to how much stuff I'm juggling but summer is definitely lighter.
Desember through January is usually slow until February when things start to pick up and run steady to the start of summer.
July is pretty slim work wise, but August comes with overflow of projects that usually die out somewhere around November.
It totally varies. I've been absolutely slammed for January and February, yet my fall was one of the slowest I've had since going freelance. The only trend I've seen is that there is no trend. But then again, I work mostly in reality TV.
Normally March/April has been slower for me in the past, but this year, I've been slammed and am already fully booked till the end of May. Summer through to Dec is always busy, so hopefully if that trend continues, this will be a very good year!