Why is there a weather forecast for each race when it's irrelevant?
It says, for eco, that it's raining in China at the moment, and that it's due to rain tomorrow too. The actual weather in China also says it's going to rain all that time yes in the game it could be dry and warm.
Yes, even though it was lowered the temperature is still capped so it won't go down far enough for the game to have snow, so basically it's a wet race. However there's actually a different setup if it's snowing in real weather, in between the normal rain and the monsoon one.