June through October is monsoon season in Thailand, the temperatures moderate but the rain can be heavy, reaching over 300 mm in the capital in September. Naturally, an umbrella is more than useful. Many welcome the rains as it brings cooler temperatures than the scoring temperatures of earlier in the year, though it is still between 24 and 30 ºC (75-86ºF) in most areas. In the north and central regions, the rains bring a vibrant green back to the hills and countryside, with many flowers coming into bloom. The monsoons give depth and added speed to the many beautiful rivers and waterfalls. Slightly muddy conditions can be expected if you plan on trekking in the Golden Triangle region.