For Rails apps running on Heroku, by default Time.now and some_time.localtime will display in UTC. If you’d like to assign a timezone to your app, you can set the TZ config variable to a time zone (which must be in the tz database timezone format).
Personally I despise the tz database format, because it requires you to guess WHICH city is chosen to represent that time zone (for Pacific, it’s LosAngeles, not Seattle, not SanFrancisco). But that’s what Heroku uses, so to set your app to Pacific you simply run:
heroku config:add TZ="America/Los_Angeles"
The allowed options are listed on the page linked above.