"Winter is coming."
I think you could easily argue that the arrival is a future event, but venado is a process that takes time. If it's already started coming then it is coming now, even if it hasn't arrived.
Present tense is also used for repeated events - Vintro venas ĉiun jaron.
You're right though that in English we often use present tense for future events.
- My mother is coming on Friday.
For that I actually would expect future tense, because she hasn't started yet.