const options = {
  method: 'GET',
  headers: {
    'X-RapidAPI-Key': '9275b62a1fmsh3b832340dafb492p1abc77jsn58ef554feee6',
    'X-RapidAPI-Host': 'forecast9.p.rapidapi.com'
  }
};

var response = fetch('https://forecast9.p.rapidapi.com/rapidapi/forecast/Berlin/hourly/', options)
  .then(response => response.json())
  .then(response => console.log(response))
  .catch(err => console.error(err));