gistfile1.php

<?php

$ttl = 5 * 3600;
$refresh_time_limit = strtotime('2013-04-07 13:00'); // variable_get
$limit = 10;     // variable_get
$max_limit = 450; // variable_get

$now = time();  // 12:15
$is_hour = ($now - $refresh_time_limit) > 3600; // true

$city_name = 'Чебоксары';

if ($limit < $max_limit) {
  $refresh_time_city = strtotime('2013-04-07 08:00');
  $is_city_ttl_over = ($now - $refresh_time_city) > $ttl; // true

  if ($is_city_ttl_over) {
    $city = get_city_from_api($city_name);
    save_to_database($city);
    print_city($city);
  }
  else {
    $city = load_from_database($city_name);
    print_city($city);
  }
}
else {
  if ($is_hour) {
    $refresh_time_limit = $now;
    $limit = 0;

    $city = get_city_from_api($city_name);
    save_to_database($city);
    print_city($city);
  }
  else {
    echo '<h1>Пустой город</h1>';
  }
}

function get_city_from_api($city_name) {
  return 'Чебоксары - 5 градусов';
}

function save_to_database($city) {
  file_put_contents('weather.txt', $city);
}

function print_city($city) {
  echo '<h1>Погода в городе ' . $city . '</h1>';
}

function load_from_database($city_name) {
  return file_get_contents('weather.txt');
}