but I'm hoping it has something to do with the temperature/season.

Yeah, I was going to mention something about that; now that you remind me...

Insomnia may (or may nor) be solved by one or more of: (roughly in order of perceived-by-me importance) making sure the temperature in your room is not too high (or too low), using LeechBlock or something to prevent you from surfing the Web past a certain time, not spending too much time in your room (especially in bed) doing things other than resting (or intimate activities), biphasic sleep (I usually sleep around six hours and a half every night and take a one-hour nap in the afternoon), lots of light/water/caffeine until dinner but very little afterwards, and software that decreases the colour temperature of your display (such as F.lux or Redshift).

(I still wonder how could I spend the first two decades of my life having serious trouble falling asleep pretty much all summer nights but seldom in the winter, before it occurred to me that keeping the windows open for a couple hours after sunset to let cooler air in might solve most of the problem.)