Surabaya is warmest in September, averaging 34° by day and 26° at night. The wettest month is December with 481 mm, and the year brings about 2324 mm in total.
Month by month
| Month | High | Low | Rain | Sea | Daylight | Good for |
|---|---|---|---|---|---|---|
| January | 29° | 26° | 347 mm | 30° | 12.4 h | Rainy season |
| February | 29° | 26° | 414 mm | 29° | 12.2 h | Rainy season |
| March | 29° | 26° | 270 mm | 30° | 12.0 h | Rainy season |
| April | 30° | 26° | 222 mm | 30° | 11.8 h | Rainy season |
| May | 31° | 26° | 121 mm | 30° | 11.7 h | Mild |
| June | 31° | 25° | 84 mm | 29° | 11.6 h | Beach weather |
| July | 31° | 25° | 43 mm | 28° | 11.6 h | Beach weather |
| August | 33° | 25° | 12 mm | 28° | 11.8 h | Beach weather |
| September | 34° | 26° | 42 mm | 29° | 12.0 h | Beach weather |
| October | 33° | 27° | 87 mm | 30° | 12.2 h | Beach weather |
| November | 31° | 27° | 201 mm | 30° | 12.3 h | Rainy season |
| December | 30° | 26° | 481 mm | 30° | 12.4 h | Rainy season |
High and low are average daily maximum and minimum, rain is typical monthly total, sea is the average surface temperature, daylight is the hours between sunrise and sunset mid-month. Climate normals from NASA POWER and NOAA MUR — averages, not promises.
When to go
Beach weather: June, July, August, September and October — highs around 32°, nights no colder than 25°, and at most 87 mm of rain in a month. The sea sits at 28–30° then.
Wet season: January, February, March, April, November and December — up to 481 mm in a single month.