  The El Ni\~no Southern Oscillation (ENSO) is the most important driver of
interannual global climate variability and can trigger extreme weather events
and disasters in various parts of the globe. Depending on the region of maximal
warming, El Ni\~no events can be partitioned into 2 types, Eastern Pacific (EP)
and Central Pacific (CP) events. The type of an El Ni\~no has a major influence
on its impact and can even lead to either dry or wet conditions in the same
areas on the globe. Here we show that the zonal difference $\Delta T_{WP-CP}$
between the sea surface temperature anomalies (SSTA) in the equatorial western
Pacific and central Pacific gives an early indication of the type of an
upcoming El Ni\~no: When at the end of a year, $\Delta T_{WP-CP}$ is positive,
an event in the following year will be probably an EP event, otherwise a CP
event. Between 1950 and present, 3/4 of the EP forecasts and all CP forecasts
are correct. When combining this approach with a previously introduced
climate-network approach, we obtain reliable forecasts for both the onset and
the type of an event: at a lead time of about one year, 2/3 of the EP forecasts
and all CP forecasts in the regarded period are correct. The combined model has
considerably more predictive power than the current operational type forecasts
with a mean lead time of about 1 month and should allow early mitigation
measures.
