Hilo (HI) Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in Hilo, Hawaii, United States of America. The numbers reflect climate data gathered over a 30-year period, from 1990 to 2020. Now, let's explore all the details to give you a full picture.

Hilo is known for its substantial rainfall, with annual precipitation reaching 2136 mm (84 in). While the overall climate is wet, there are notable seasonal patterns that create interesting contrasts, as demonstrated in our graph below.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm (0.01 in))

Significant seasonal changes in precipitation occur throughout the year. During the wettest month, March receives substantial rainfall, averaging 273 mm (11 in) of precipitation, recorded across 19 rainy days.

In contrast, the driest month, June brings less rainfall, with 117 mm (4.6 in) over 18 rainy days.

March, the wettest month, has a maximum daytime temperature of 23°C (73°F). The city receives 154 hours of sunshine in this period. During the driest month June you can expect a temperature of 25°C (77°F). For more detailed insights into the city's temperatures, visit our Hilo Temperature page.

Hilo's average annual precipitation is 2136 mm (84 in). Let's compare this to some popular worldwide tourist destinations:

In Barcelona, Spain, the average annual precipitation is 644 mm (25 in), evenly distributed across the year with no extreme wet or dry seasons.

Osaka, Japan, experiences 1507 mm (59 in) of rainfall annually, spread across the year with wetter summers.

Melbourne, Australia, has 690 mm (27 in) of rainfall annually, spread fairly evenly throughout the year.

Singapore, situated near the equator, gets 2581 mm (102 in) of rainfall annually, with no distinct dry season and consistent monthly precipitation.

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

Climate change is affecting precipitation patterns worldwide, including Hilo (HI):

• Changing Rainfall Patterns: Global warming causes drastic changes in the patterns of rainfall. Some areas have been experiencing increased frequency and intensity of rainfall, while other areas experience longer dry spells or even droughts.
• Local Impacts: Many regions are experiencing heavier rainfall in the winter months and drier, hotter summers. This affects agriculture, water resources, and ecosystems.

• Mawsynram in India is noted as being the wettest place on earth, with over 11 meters (36 feet) of rain falling every year.
• In contrast, Antofagasta in Chile is among the driest places on the planet, getting less than 0.1mm (0.004 inches) per year, with some years recording virtually no rainfall.
• Nearly 1,650 thunderstorm cells are estimated over the planet at any given time.

For more detailed information about Hilo (HI)'s weather, including sunshine hours, humidity levels, and temperature data, visit our Hilo (HI) Climate page.