That has happened to me, too. I had to strip a fish carving that I had spent 5 days painting and start over.......
I usually START my models by overspraying the model sheets with a matte fixative such as KRYLON Preserve-IT before I start cutting..
Did you overspray with lacquer/alcohol base or acrylic?
Depending on what you oversprayed it with, I agree with both GreMir and
Ashville. First, try to get as much of the cloudy stuff off as you can; and then CAREFULLY spray with DullCote. All things being well, the fresh dull cote will "melt" into the cloudy stuff and sort it out.
You are right: do not spray when it is overly damp/humid or raining.
When using any kind of aerosol product, it is VITALLY IMPORTANT that you follow ALL of the following steps EVERY TIME:
1. SHAKE the spray can vigorously for AT LEAST TWO MINUTES (Count to at least 120 while continuously shaking) I usually count to 180 (3 minutes)
2. TEST the spray on a piece of dark-coloured scrap card. If it clouds, shake the can some more and test again. If it still clouds, then the spray can is NS (Non-Serviceable) and should either be tossed or returned to the point of purchase.
3. If the test is OK, Apply one light mist coat; allow to dry; apply a second mist coat and dry likewise; and then apply a third, heavier finish coat. Allow to dry THOROUGHLY before attempting to handle.
4. After each coat, INVERT the can and spray until no paint is visible. This will clear the nozzle and the valve.
Hope this helps! Good luck!
Ps: I hope that the subject wasn't your BUFFALO???