Your correspondent from Takayama is actually a weather-forecast freak. Back in the days when he was living in Hong Kong, whenever a typhoon was approaching, he would almost certainly check its latest position and predicted route every hour, and read heated discussions on weather forums about whether the observatory had hoisted a proper typhoon warning signal at a proper time (without participating). Since dear typhoons almost never grace Takayama with their presence, he thus diverted most of his energy and enthusiasm to predicting first snow. With the autumn colors fading away soon, the time has come again to hold this game among our staff. First snow normally falls around mid November in Takayama downtown area, but I’ve a feeling that this year it will fall a bit later than usual, not least the famous snow-predicting gingko tree at Kokubunji temple hasn’t yet turned completely yellow.
Humidity also matters, but in general:
3 degree Celsius: rain
2 degree Celsius: sleet
1 degree Celsius: wet snow
0 degree Celsius: snow that will stay on the ground
There was some confusion last year when my colleague and I looked out the window one day, and saw snow-like particles falling from the sky. We thus rushed out in excitement, thinking first snow at last fell, but we were later told that it was hail not snow. How embarrassing!