一种方法是使用IntlCalendar类，它有一个getFirstDayofWeek()方法，返回一个整数，对应于IntlCalendar中的**DOW_**常量：

const integer DOW_SUNDAY = 1 ;
const integer DOW_MONDAY = 2 ;
const integer DOW_TUESDAY = 3 ;
const integer DOW_WEDNESDAY = 4 ;
const integer DOW_THURSDAY = 5 ;
const integer DOW_FRIDAY = 6 ;
const integer DOW_SATURDAY = 7 ;

当调用DateTimeImmutable::modify()作为开始日期时，使用它将天数添加到开始日期。请在this phpfiddle中查看它在三个语言环境（即 en_US、es_ES、sw_KE）中的实际操作。

$locale = 'es_ES'; //Spain Spanish locale
$cal1 = IntlCalendar::createInstance(NULL, $locale);
$firstDayOfWeek = $cal1->getFirstDayOfWeek();
$daysToAdd = $firstDayOfWeek - 2; //difference from US M-Sunday 
echo 'locale: '.$local.' first day of week: '.$cal1->getFirstDayOfWeek().' days to add: '.$daysToAdd.'<br />';
$start_week = new DateTimeImmutable();
$start_week = $start_week->modify('this week +'.$daysToAdd.' days');
$end_week = $start_week->modify('+6 days');
$interval = new DateInterval('P1D');
$week_range = new DatePeriod($start_week, $interval, $end_week);

foreach($week_range as $week_day) {
    echo 'week day: '.$week_day->format('l m/d/Y').'<br />';
}

IntlCalendar可以完成所有这些工作，但没有很好的文档记录。
其他答案使用一些硬编码的值，但这个答案没有。

$date = new DateTime('now');
$locale = 'en_US';

$thisWeek = IntlCalendar::fromDateTime($date, $locale);
$thisWeek->set(IntlCalendar::FIELD_DAY_OF_WEEK, $thisWeek->getFirstDayOfWeek());
// $thisWeek now points to the first day of the week
$weekStart = $thisWeek->toDateTime();

$daysToAdvance = $thisWeek->getMaximum(IntlCalendar::FIELD_DAY_OF_WEEK) - 1;
// Maximum number of days in a week minus 1 gets you to the last day
$weekEnd = $weekStart->modify("+{$daysToAdvance} days");

$previousWeek = IntlCalendar::fromDateTime($date, $locale);
$previousWeek->add(IntlCalendar::FIELD_WEEK_OF_YEAR, -1);
$previousWeek = $previousWeek->toDateTime();

$nextWeek = IntlCalendar::fromDateTime($date, $locale);
$nextWeek->add(IntlCalendar::FIELD_WEEK_OF_YEAR, 1);
$nextWeek = $nextWeek->toDateTime();