  We assess the skill and reliability of forecasts of winter and summer
temperature, wind speed and irradiance over China, using the GloSea5 seasonal
forecast system. Skill in such forecasts is important for the future
development of seasonal climate services for the energy sector, allowing better
estimates of forthcoming demand and renewable electricity supply. We find that
although overall the skill from the direct model output is patchy, some
high-skill regions of interest to the energy sector can be identified. In
particular, winter mean wind speed is skilfully forecast around the coast of
the South China Sea, related to skilful forecasts of the El Ni\~no--Southern
Oscillation. Such information could improve seasonal estimates of offshore wind
power generation. Similarly, forecasts of winter irradiance have good skill in
eastern central China, with possible use for solar power estimation. Much of
China shows skill in summer temperatures, which derives from an upward trend.
However, the region around Beijing retains this skill even when detrended. This
temperature skill could be helpful in managing summer energy demand. While both
the strengths and limitations of our results will need to be considered when
developing seasonal climate services in the future, the outlook for such
service development in China is promising.
