June is generally the 'Plum Rain' season in Taiwan. Like all weather it's unpredictable, impossible to say when it will arrive or how long it will last. At this time if you get a bad forecast it would be better to reschedule trips to high mountains. This year we were lucky with two successful trips going out in June to both Jade and Snow Mts. We only had to alter plans on one trip. In February of each year Jade Mt. is closed for snow season.