The coldest I've ever been was 45 degrees in Houston - can't hide from the humidity.

Either lighten the front or weight the rear (using Homer Simpson's best "doh!") - just kiddin' ...

Was this a kit or ARF? What's the engine?

I usually take some kind of incremental weight (bearings, BB's, bullets, cat litter) that can be put in a zip lock and weighed. Then you can sling the bag on the bottom of the fuse when you check the balance CG. Figure out how much you need to move the CG. You are balancing the plane upside down, right?

Then guys have used a number of 1/4 oz lead weights epoxied to the side of the fuse under the stab. Cut a bit of film to expose the balsa & epoxy in place. I've been known to drill 1/16" holes thru the lead to allow the epoxy to squeeze thru and provide a bit better mechanical bite.

Other things include swapping a heavy hub on your engine with an an aluminum one.
Move the fuel tank to the back of the tank "bay".
Lighter wheels (foam) because that's in front of the CG.
Move the servos back (easier with a kit) - some mount an elev or rudd servo to the back just in front of the fin / stab. Requires a long extension.
Tie your neighbors pet mouse to the tail (just messin').

HTH

Just sign me - Angleton visitor in a couple of weeks ...