Perfect

Just to show you what I meant:

iex> Tzdata.zone_exists?("MST")
true
iex> Tzdata.zone_exists?("MDT")
false # <- see here

iex> Timex.now("MDT")
#DateTime<2020-03-26 19:55:03.637000-06:00 MDT MST7MDT>

“MDT” doesn’t exist as a time zone ID, but Timex will find a time zone ID that contains the string “MDT”, and finds MST7MDT, whish does change according to US DST rules.

Ouch… I don’t know why Timex would not return an error instead honestly, that leads to bugs ;-p

If one ever needs a fixed offset, better use a time zone ID such as Etc/GMT-7.

Anyway, it was just to complete the information. You use the right time zone ID now.

I think I confuse you more:) but the IANA tz database can be very confusing.

“MST” can be used as a time zone ID; but for example “MDT” seems not to be a valid time zone ID.

^ So this should actually throw an error

Anyway, this is not what you want. You want to use “America/Denver” as a time zone ID.

When you use “America/Denver” as a time zone ID, the offset will change throughout the year:
-07:00/MST and -06:00/MDT

This is actually how timezones work. Timezone names alike MDT are names for certain UTC offsets. Area names like “America/Denver” are the names, which define which of those timezones is in effect in a certain area of the world at a certain time.