Wunderground is no longer giving out free new API keys. The service is still up for the current users, but not sure how long it will last.
The Wunderground component will not work for new users who can’t get API keys for free. The cheapest option from IBM Business is $850/month.
“To improve our services and enhance our relationship with our users, we will no longer provide free weather API keys as part of our program. If you have been directed to download our Weather Underground free API key by a third party provider, please contact your vendor for resolution.”
Source: https://www.wunderground.com/weather/api/
https://apicommunity.wunderground.com/weatherapi/topics/weather-underground-api-changes