How accurate are weather forecasts?

In the following charts forecast accuracy is presented in terms of Root Mean Square Error. So lower values are better. And 0 would be perfect score. A baseline benchmark is included corresponding to trivial predictions: forecasts for the next 5 days being the same as today's weather.

Temperature forecasts error checks both min. and max. temperature predictions in º Celsius:

Precipitation forecasts error applies to predicted probabilities (range: 0 to 1). It is equivalent to the square root of Brier Score.

Observed locations: Madrid-Barajas Airport, Madrid (Spain), Atlantic City International Airport, New Jersey (USA), Macau International Airport, (Macau)

Period: August 20th, 2013 to January 21th, 2014.

More data coming soon: weather sources, locations, accuracy metrics, reports, challenges...