Detect if British Summer Time is in effect

is_bst.php

/* Refactored to check actual timezone abbreviation versus a particular day */

public function is_BST() {
	$theTime = time();
	$tz = new DateTimeZone('Europe/London');
	$transition = $tz->getTransitions($theTime, $theTime);
	$abbr = $transition[0]['abbr'];

	return $abbr == 'BST' ? true : false;
}

/* Old gist
public function is_BST() {
	$today = strtotime("today");
	$year = date('y');
	$BSTstart = strtotime($year."-03-31 last Sunday");
	$BSTend = strtotime($year."-10-31 last Sunday");
	if ($today < $BSTstart || $today > $BSTend) {
		return false;
	} else {
		return true;
	}
}
*/