Obtaining Weather API
To obtain free API KEY register at https://developer.forecast.io/register
Click the button “TRY FOR FREE” and fill the registration form (2).
You will receive an e-mail to complete the registration. Click the link in the e-mail.
Now your account is ready and after login in you will see this screen with your API key (4).
Copy the key and go to Stachethemes Event Calendar General Settings and paste it in the Weather API Key field (5).