Anyone know where I can find some stats on the seasonal water temperatures of local lakes.  I'm especially interested in Saguaro and Canyon.  I'm less concerned with how hot they get as I am how cold they get.  This is for a wetsuit purchase.  thanks

I don't have any set data, but as a regular diver at those lakes I can give you temperature variants between warm and cold.
During the summer temperatures can reach 80 degrees with the thermocline running about 10 to 15 degrees cooler (@ 15-20 feet).
During the cooler months like January, surface temps run about 20 degrees cooler on average with the thermocline starting about 8-10 feet.
Once you get to 35+ feet, temperature can run an additional 10 to 15 degrees cooler than thermocline temp, depending on any currents and upswell.
During high summer I just go with a bathing suit, Winter I will go with a 7 mil full, and spring is 3 mil shorty weather.
I do have a high tolerance for cold, so YMMV.

ETA:
These figures are just averages I have compiled over about 8 years, varables such as weather patterns, ice ages, and global warming may affect your comfort level.

Quoted: ETA: These figures are just averages I have compiled over about 8 years, varables such as weather patterns, ice ages, and global warming may affect your comfort level.

Thanks Gunslinger808!  I don't dive, rather I ride a stand-up PWC.

I looked all over (seemed so anyway) and couldn't find squat.  That info helps.  I figured maybe around 60 was as cold as I would find (at the surface).  I don't know much about the composition of lakes (I had to look up "thermocline") so thanks for that education.

Where on those lakes do you dive?  Can you see anything down there?