There are lots of questions about Trolltunga hiking season. Please read before you ask a question:
Because of remaining snow the hike can only be done from late June.
Because of short daylight and Winter conditions at high altitudes the hike should in no case be attempted after October 15th. Even before October there can be snow and frost on the trail, after September 15th hike with a guide.
Wind and rain can make the hike cold even in summer. Be prepared to do another, less demanding hike instead. Rule # 8: Don’t be ashamed to turn around.
In Norway, signs and warnings are used sparingly and understatements are common. If you see a sign, there is a very good reason.
Advice and news reports about Trolltunga