<?php
if (! wp_next_scheduled ( 'my_hourly_event' )) {
	wp_schedule_event(time(), 'hourly', 'my_hourly_event');
}

add_action('my_hourly_event', 'do_this_hourly');

function do_this_hourly() {
	update_option('show_my_notification', true);
}

/**
* Run This in Where in Your Notifications HTML
*/
function show_my_notification() {
  if(get_option('show_my_notification')){
    // Put Your Notification HTML or Function
    update_option('show_my_notification', false);
  }
}