- If no timezone is in the date format, assume localtime and move to UTC time.

lib/log.rb

@@ -96,8 +96,15 @@ module LogStash
         end
       end
       time ||= DateTime.now
+      # Store times in UTC, so subtract 
       res["@DATE"] = time.strftime("%s").to_i
 
+      # Assume local timezone if the date format for this log doesn't
+      # include a timezone offset
+      if !@config[:date_format].include?("%Z")
+        res["@DATE"] -= Time.now.gmtoff
+      end
+
       return res
     end