I don't have an answer but the usual way to tell is by the eye pigmentation. Since his eyes aren't normal albino eyes it might be impossible to tell by visual clues alone. I'll be interested to hear if anyone has a method though! Very cute little guy!
Where did you buy it from? If bought from a pet shop without even thinking about it I'd say tremper, it's a lot more common. Rw blazing blizzards aren't the rarest but I'd say its a lot harder to find then a tremper version.
Here's a pair of female rainwater blazing blizzards and they look a little different from each other, but same strain.
To be positive you have to test breed... someone else might have a theory, but to be absolutely sure, you have to testbreed.
hope this helps you out a little.