If the time zone that you are in is currently on daylight savings time you must adjust this to standard time.
Daylight savings time in the summer half of the year is always an hour ahead so you must take off an hour.
So for example, if you are in the USA in July your clock has been put forward (Spring forward) so you must take off an hour to get standard time. In winter months you need not adjust the clock.
If you are using a digital clock or watch to assertain the current time, draw an analogue clock on a piece of paper (or something that you can move around) which shows a clock face telling your standard time (the time that you may have adjusted in Step 1 above).
Point the hour hand towards the sun. If it is overcast you can often get the sun's direction from shadows (it is in the opposite direction to the sun's shadow).