The skill of hindcasts of the European Centre for Medium-Range Weather Forecasts in forecasting heat wave days (periods with the 5-day moving average temperature being above its local summer 90th percentile) over Europe 1 to 4 weeks ahead is examined. The heat wave days forecasts show potential in warning of heat risk in 1–2 weeks in advance, and enhanced accuracy in forecasting prolonged heat waves, in lead times of up to 3 weeks, when the heat wave had initiated prior to the forecast issuance.

Wind speed forecasts have many potential users that could benefit from skilful forecasts. We validated weekly mean speed forecasts for Finland using forecasts from the ECMWF (European Centre for Medium-Range Weather Forecasts). We concentrate on winter (November, December and January) forecasts. The forecasts proved to be skilful until the third week, but the longest skilful lead time depends on how the skill is calculated and what is used as the reference.

We studied the applicability of seasonal forecast outputs in agriculture in Finland. The quality of seasonal forecasts output was assessed, and six tailored seasonal forecast indices were co-designed, developed in close collaboration with the Central Union of Agricultural Producers and Forest Owners and piloted with over 200 farmers. Although the tested seasonal forecast indices had a limited skill and need further improvements, the farmers found the climate outlooks useful.

Reanalysis data of the strength of the polar vortex is applied in the post-processing of the European Centre for Medium-Range Weather Forecasts (ECMWF) winter surface temperature forecasts for weeks 3–4 and 5–6 over northern Europe. In this way, the skill scores of these forecasts are slightly improved. It is also found that, in cases where the polar vortex was weak at the start of the forecast, the mean skill scores of these forecasts were higher than average.

Finnish Meteorological Institute and Helen Ltd examined the feasibility of long-range forecasts (longer than two weeks) of temperature for needs of the energy sector in Helsinki, Finland. In this study, we examined the quality of Heating degree day (HDD) forecasts. As the forecasts we used UK Met Office seasonal forecasts. The long-range forecasts of monthly HDD showed some skill in Helsinki in winter 2015–2016, up to two months, especially if the very cold January is excluded.