title: Determine if UTC Time is in DST for a given Timezone
body: <p>I have a time, in UTC. I also have a "Room" assignment, which has <em>partial</em> timezone information associated with it (it's got a location, so I know if it's Eastern, Pacific, etc).</p>
  
  <p>I need to take the UTC time, and convert it to the "target" timezone. However, the date could be in the future or the past, so the "target" timezone needs to be "Standard" or "Daylight" according to the appropriate timezone rules.</p>
  
  <p>So, I want something like this:</p>
  
  <pre><code>TimeZoneInfo.ConvertTimeFromUtc(UTCDateTime, TimeZoneInfo.FindSystemTimeZoneById(tz));
  </code></pre>
  
  <p>But I don't know how to get "tz", since all I know is that it's (for example) a PST <em>or</em> PDT value, I don't know which one.</p>
  
  <p>How should I approach this?</p>