Parsing DateTime with a known but not given time zone

I'm stuck with a problem around parsing date and time:

I'm trying to parse a datetime string extracted from a german website. It is given in the format 'day.month.year 24hours:minutes', like:

01.01.2011 17:00

And it is always in the german timezone. But here comes the problem:

• '01.01.2011 17:00' should be parsed to a DateTime struct with '01.01.2011 16:00' in UTC (here, the timezone is CET, without daylight saving time)
• while '01.06.2011 17:00' should be parsed to a DateTime struct with '01.01.2011 15:00' in UTC (here, the timezone is CEST, with daylight saving time)

I have no clue how to achieve this. If I set my local clock to the german timezone, and I parse with DateTime.ParseExact and the flag DateTimeStyles.AssumeLocal and DateTimeStyles.AdjustToUniversal it is parsed correctly. However, I want any client to parse it independently from their local clock and timezone. Also, I dont want to do the timezone offset myself, because it depends on the date (summer: -2 / winter: -1).

Once I have the datetime in UTC it would be easy to convert it to any local timezone.