Daylight Saving Time (DST) is a system of setting the clock ahead by one hour during the warmer months to extend the amount of daylight in the evening. The specific dates for the start and end of DST vary by country and region, but they are typically set by government authorities.
In the United States, the start of DST is usually on the second Sunday in March at 2:00 am local time. At that time, clocks are set forward by one hour, so 2:00 am becomes 3:00 am. This change results in one hour less of daylight in the morning, but one hour more of daylight in the evening.
It's important to note that not all countries observe DST, and even those that do may have different start and end dates. For example, in the European Union, the start of DST is usually on the last Sunday in March, but some countries may have different rules.
In Python, you can use the pytz library to convert between local time and UTC time, taking into account DST rules for the specified time zone. Here's an example of using pytz to convert a local date and time to UTC time:
import datetimeimport pytz# create a local date and time for the start of DST in the USdt_local = datetime.datetime(2023, 3, 12, 2, 0, 0)# create a timezone object for the US Eastern time zonetz = pytz.timezone('US/Eastern')# convert the local time to UTC timedt_utc = tz.localize(dt_local, is_dst=None).astimezone(pytz.utc)print(dt_local)# output: 2023-03-12 02:00:00print(dt_utc)# output: 2023-03-12 07:00:00+00:00 |
In this example, we create a datetime object for the start of DST in the US and a timezone object for the US Eastern time zone. We then use the localize() method to attach the time zone information to the datetime object and set the is_dst parameter to None to indicate that we don't know whether DST is in effect at that time. Finally, we use the astimezone() method to convert the local time to UTC time, taking into account the DST rules for the specified time zone.