PHP daylight saving time detection

Question

I need to send an email to users based wherever in the world at 9:00 am local time. The server is in the UK. What I can do is set up a time difference between each user and

Answer 1

Changing my answer a bit: DateTimeZone::getTransitions looks like it will do what you need, provided you have PHP >= 5.2.

From a comment in the documentation:

getTransitions($theTime, $theTime); 

// only one array should be returned into $transition. Now get the data: 
$offset = $transition[0]['offset']; 
$abbr = $transition[0]['abbr']; 
?>

So here, all we need to do is pass in the timezone we want to check and we can know if that timezone is in DST/what the offset is. You'll then need to check the offset against GMT to see if you want to send your e-mail now, or not now.