Kalaw in October

Cool season (November through March) is peak time for good reason. Days are sunny and pleasant at 20-25°C, while nights drop to 5-10°C. You'll actually need that sweater you packed. This is prime trekking weather, but also when accommodation fills up fastest. Hot season (April-May) sees temperatures climb to 30°C+ during the day, though it's still cooler than the rest of Myanmar. Rainy season (June-October) brings daily afternoon showers and misty mornings. Some trek routes become muddy and difficult, but you'll have the town mostly to yourself. Plus, everything is incredibly green.