$apiKey = 'your api key';
$request = new CityRequest($apiKey);
$request->setFormat(CityRequest::FORMAT_JSON); // json is default format
$request->setNumberOfDays(3); // default 2
$request->setCity('New York');
$request->setCountry('USA');

$proxy = new CurlProxy();
$response = $proxy->performRequest($request);
if($response->getSuccess()) {
    echo $response->getCurrentWeather() . "\n";
    foreach($response->getWeatherList() as $weather) {
        echo $weather . "\n";
    }
} else {
    foreach($response->getErrors() as $error) {
        echo $error . "\n";
    }
}

TODO:

Implementation of XML Response format
Implementation of CSV Response format
Tests