As per Yahoo weather developers site:
As of Thursday, Jan. 3, 2019, the weather.yahooapis.com and query.yahooapis.com for Yahoo Weather API will be retired.
To continue using our free Yahoo Weather APIs, use https://weather-ydn-yql.media.yahoo.com/forecastrss. Follow below instructions to get credentials and onboard to this free Yahoo Weather API service.
The mashup code uses yahoo API to compare temperature from a given location to Pi's location. Now it is easy for me fork the code and implement the newer or changed API but it requires an API key.