Sounds like you're getting close!
The ambient air temp won't much matter, except for a longer warm up for the engine. But the blower will be fine at cold temps. It will tend to lean the air/fuel mixture.
If you have a forward-facing scoop, there will be water entering the blower, no doubt. AFA how much water can be ingested w/o issue, or the effects of the water entering the blower, I do not know. Obviously, smaller amounts will be handled w/o problem- a common anti-knock addition is water injection. But past some point, the water will be excessive and will start to richen the A/F mixture by displacing the air.
I would imagine (but do not know for certain) that before the A/F mix would be excessively rich for any length of time, that the engine would stall.
There are ways to keep the air filters relatively (or completely) dry in the rain, but this would require a different set-up than a "traditional" blower scoop.