Is a wind speed of 150 km/h dangerous during a flight in an Airbus A321?
High windspeeds themselves are not a problem, but the environment surrounding them may be.  

For example, in the wintertime it is not uncommon to find a strong core of fast winds embedded within the polar jetstream.  We term this windspeed maximum a 'jet streak'.  There are a couple of meteorological phenomena associated around these jetstreaks, such as regions of ascent and descent in the entrance and exit regions of the jetstreak and often times turbulence in the periphery.  You'll also find regions of turbulence on the lateral extent of the jetstream (polar side in particular).  Lastly, if you are flying at an angle to the jetstream or perpendicular to it, you will often experience changing wind direction along with speed, and this can be turbulent.

There is nothing dangerous about that wind speed alone.  What likely happened is that other airplanes were reporting turbulence and the pilots were being cautious with you and just offered that wind speed up as an easily understood number to justify the precaution.