Yep: flashes are set to a colour temperature of ~5200K-6000K (the target actually being 5500K, the temperature of mid-day sunlight in a clear sky). During the golden hour the daylight temperature is warmer and oranger, so you need to compensate for that. Also note that Canon flashguns seem to be on the low Kelvins side, roughly ~5200K; furthermore, as you might already know, flashguns' colour temperature also varies with power level. All in all, a CTO should solve your problems at the cost of 2/3 to 1 stop of light.
Maybe this might help you: http://profoto.com …ce-using-cto-gel-ctb-gel/
. They explain things better than I do. 