Current conditions at :
At just around seven degrees south of the equator, Surabaya has a remarkably constant climate. Temperatures remain almost constant throughout the year, with only a couple of degrees variation in both high and low temperatures from month to month. You can find more information and long range forecasts for Surabaya at Weather Underground.
Five-Day Weather Forecast for Surabaya
Historical Weather Patterns for Surabaya
The main difference through the year is the amount of rain. August and September are the driest months, while the rains are quite heavy from December to March.