The climate of the Southwest Pacific is dominated by the the South Pacific Convergence Zone (SPCZ). It occurs where the southeast trades from transitory anticyclones to the south meet with the semi permanent easterly flow from the eastern South Pacific anticyclone. The SPCZ exists in summer and winter but can change its orientation and location. The location of the SPCZ is affected by ENSO and Interdecadal Pacific Oscillation conditions. It generally stretches from the Solomon islands through Vanuatu and Fiji. Low level convergence along this band forms cloudiness as well as showers and thunderstorms. Thunderstorm activity, or convection, within the band is dependent upon the season, as the more equatorward portion is most active in the Southern Hemisphere summer, and the more poleward portion is most active during transition seasons of fall and spring. The convergence zone shifts east or west depending on the existence of El Niño, or the phase of ENSO and can have considerable impacts on drought and extreme rainfall and heightened or reduced cyclonic activity across the region. PNG with its higher elevations can suffer from extreme cold and frost and this can compound drought conditions that usually coincide with ENSO activity.