How to check if date is in UTC format using pytz or datetime?

Question

I'm using the pytz module to translate a date from America/Los_Angeles timezone to UTC using the code below:

TZ = 'America/Los_Angeles'
from = pytz.timezone(TZ)
utc = from.localize(original_date).astimezone(pytz.utc)

Now, I want to test if the UTC value is actually in UTC format or not. How to do that with pytz or datetime ?

score 8 · Answer 1 · edited Aug 04 '23 at 01:05

8

The accepted answer will not work for anything else other than pytz objects. As pytz is actually pretty bad at doing conversions [1] (e.g. properly doing daylight savings, etc.) it is probably better to do a cross-implementation check.

now = datetime.datetime.now(pytz.utc)
if now.tzinfo:
    now.utcoffset().total_seconds() == 0 # returns true

[1] https://pendulum.eustace.io/blog/a-faster-alternative-to-pyz.html

edited Aug 04 '23 at 01:05

Gino Mempin

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answered Aug 06 '18 at 08:45

Bolke de Bruin

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Thanks, this one bit me when accepting input from a library that used dateutil, while I used pytz. – theY4Kman Oct 04 '18 at 04:34
Just as a note, `total_seconds()` [returns a float](https://docs.python.org/3/library/datetime.html#datetime.timedelta.total_seconds). While it's unlikely that you'll encounter a situation where comparison to integer 0 fails, you could be sure by using `int(now.utcoffset().total_seconds()) == 0` – idoimaging Oct 31 '19 at 19:31
@idoimaging `int(now.utcoffset().total_seconds()) == 0` gives True if the timezone is GMT... `datetime.now(pytz.timezone("GMT"))`. GMT and UTC time are the same apparently. – theQuestionMan Mar 07 '22 at 13:38

score 7 · Accepted Answer · answered Jul 15 '11 at 12:00

7

utc.tzinfo == pytz.utc # returns True if utc in UTC

Example:

now = datetime.datetime.now(pytz.utc)
now.tzinfo == pytz.utc # returns True

now = now.astimezone(pytz.timezone('America/Los_Angeles'))
now.tzinfo == pytz.utc # returns False

answered Jul 15 '11 at 12:00

eumiro

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Any example without pytz? – alexche8 Feb 15 '16 at 14:53
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@alexche8 , `import dateutil` `import datetime` `now = datetime.datetime.now(dateutil.tz.tzutc())` `now.tzinfo == dateutil.tz.tzutc()` – nikpod Aug 31 '17 at 03:37
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`datetime.timezone.utc != pytz.utc`, so this fails or dates using a standard utc timezone object. – Mitar Apr 17 '18 at 12:04

score 0 · Answer 3 · answered Mar 08 '22 at 03:47

You can do it simply like this:

from datetime import datetime, timezone
lunch_time = datetime.now(timezone.utc)

if lunch_time.format('%Z') == 'UTC':
     print("Eat food")

This will also work with a naive time object because lunch_time.format('%Z') will return an empty string. This method will also work with pytz or any other module because you are simply checking the timezone as string not as an object (the accepted answer won't work with the above timezone module case, only pytz).

from datetime import datetime
import pytz
dinner_time = datetime.now(pytz.timezone('UTC'))

if dinner_time.format('%Z') == 'UTC':
     print("Hungry!")

Note: This will also eliminate the possibility of the timezone being GMT timezone rather than UTC timezone. The other answer now.utcoffset().total_seconds() == 0 will be True for GMT which may not be what you want.

The %Z specifier is documented here:
https://docs.python.org/3/library/datetime.html#strftime-and-strptime-behavior

score 0 · Answer 4 · answered Jun 03 '23 at 13:34

Similar to a previous answer, you can do it like this:

If you have a given datetime object, you want to first convert it to a string with the strftime() method, then pass in the %Z specifier which gives the timezone name returning one of '(empty), UTC, GMT' according to the documentation.

so an example is:


def check_if_utc(my_datetime):
   return my_datetime.strftime('%Z') == 'UTC'

How to check if date is in UTC format using pytz or datetime?

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