Periscopes seasonal overview
Best Surf Season (May - September)
Periscopes hits its stride when the seasonal migration of the ITCZ flips Indonesia into the dry season. The northwest monsoon collapses, southeast trade winds build, and a sustained easterly flow out of the NE, ENE, E and ESE takes control of the coast. The Southern Hemisphere storm track also becomes highly active during this stretch, firing long-period SSW/SW groundswell up into the west-facing bight. Wave heights average 1.5-1.8m (5-6ft) with periods around 14 seconds, and the wind is ideal 81-96% of the time. This is the window when Periscopes is consistently glassy, powerful and firing.
Fair Surf Season (April, October and November)
These shoulder months straddle the monsoon transitions. April sees the wet season departing as the southeast trades strengthen, while October and November are the mirror image: the trade-wind flow weakens and westerly monsoon pulses begin to creep back in. Swell remains very consistent from the SSW and SW, often 1.3-1.5m (4-5ft) with 13-14s energy, but the percentage of ideal wind drops to 52-78%. On the best days you get clean, head-high waves; on the others, a lumpy cross-shore breeze keeps the lineup from ever feeling truly world-class.
Low Surf Season (December - March)
From December through March, the northwest monsoon locks in across the Indonesian archipelago. Surface winds swing into the SW, WSW, W and WNW quadrants, which are directly onshore for Periscopes, and the ideal wind percentages bottom out at just 10-35%. Swell heights are still respectable at 1.3-1.4m (4-5ft) and periods stay in the low 13s, but the energy is frequently betrayed by a wind-blown, lumpy sea surface. March is the most promising of these months as the trades slowly return, but this is still the low season for quality at Periscopes.