Would that we could all have point-crawl map spreads this beautiful. Awesome, awesome, awesome.
The freezing/heat mechanic is well considered with routes for exploration likely ending in a tough question as to whether players should return to Greenleaf or not - a fine line for lock and key design that often nullifies the effects of things like cold instead - and that means crucially, that they will actually be used and seen and players will take at least some damage, experience the cold, and consequences.
That's the win from page one onwards in my book.