the_weekday()

function the_weekday() {
	global $wp_locale;
	$the_weekday = $wp_locale->get_weekday( mysql2date( 'w', get_post()->post_date, false ) );

	/**
	 * Filters the weekday on which the post was written, for display.
	 *
	 * @since WP-0.71
	 *
	 * @param string $the_weekday
	 */
	echo apply_filters( 'the_weekday', $the_weekday );
}