January weather forecast
Surabaya, Indonesia

The weather in Surabaya during the first onset of the year ushers in a warm milieu with adequate cloud cover that provides optimal conditions for outdoor activities. It is slightly warmer than December, which offers a hint of continuity in the holiday cheer. January experiences strong winds and high humidity levels, which is indicative of an active wet season with significant rainfall events. As the month with the highest recorded rainfall of 172mm, it is prudent to keep an umbrella at hand. Intriguingly, despite the presumed gloomy skies, the month still experiences an above-average duration of sunlight.

Temperature

Surabaya experiences its coldest period in January, February and July, averaging a high-temperature of 30.1°C.

Heat index

During January, the heat index is estimated at a fiery hot 37°C. Implement heightened safety measures - risk of heat exhaustion and heat cramps is increased. Prolonged activity may result in heatstroke.
In reference to the heat index, it's for places in shade and with a slight wind. The heat index might be elevated by 15 Fahrenheit (8 Celsius) degrees due to direct sun exposure.
Note: The heat index, also known as 'feels like' or 'real feel', shows a temperature sensation when both heat and moisture conditions are combined. This effect is personal, influenced by the individual's physical activity and heat sensitivity, shaped by factors including wind, attire, and metabolic variations. Recognize that direct exposure to the sun can escalate the heat effect, potentially adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values hold particular significance for children. Young people are generally more susceptible than adults because they perspire less. Furthermore, their proportionally larger skin surface to their petite bodies and the increased heat output from their actions add to the risk.
The human body keeps its cool primarily through perspiration, as this process enables sweat to evaporate, taking away the excess heat. When relative humidity is on the rise, it curtails evaporation, thereby reducing the heat elimination from the body and causing the feeling of being excessively hot. Heat absorption that surpasses the body's shedding capability can lead to overheating and varying levels of dehydration.

Humidity

The average relative humidity in January is 78%.

Rainfall

In Surabaya, Indonesia, during January, the rain falls for 27 days and regularly aggregates up to 172mm of precipitation. In Surabaya, Indonesia, during the entire year, the rain falls for 187.8 days and collects up to 839mm of precipitation.

Sea temperature

In January, the average sea temperature is 29.3°C.
Note: For water activities like swimming, diving, and more, temperatures ranging between 25°C and 29°C offer superior comfort and enjoyment for lengthy durations.

Daylight

In Surabaya, the average length of the day in January is 12h and 29min.
On the first day of January in Surabaya, sunrise is at 05:16 and sunset at 17:48. On the last day of the month, sunrise is at 05:29 and sunset at 17:55 WIB.

Sunshine

The month with the least sunshine in Surabaya is January, with an average of 8.1h of sunshine.

UV index

January through December, with an average maximum UV index of 7, are months with the highest UV index. January through December, with an average maximum UV index of 7, are months with the lowest UV index in Surabaya, Indonesia. A UV Index value of 6 to 7 symbolizes a high health risk from unsafe exposure to UV radiation for average individuals.
Note: In January, a regular UV index of 7 translates into these guidelines:
Implement preventive steps and embrace sun safety standards. Protection from skin and eye distress is compulsory. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage. Warning! Reflective surfaces like sand and water amplify the Sun's UV radiation.