Where Were O‘ahu’s Hottest Spots on the Hottest Day in 2019?

A new interactive map shows you which neighborhoods really felt the heat.
Interactive heat map of Oahu
O‘ahu community heat map allows you to zoom in to your street to see how it measured up on 2019’s hottest day.


It wasn’t your imagination. 2019 was the hottest year in recorded history on O‘ahu, according to the National Oceanic and Atmospheric Administration. According to the City and County of Honolulu, the heat set record highs 135 times and tied the daily high 138 times. And now an interactive map shows where some of the island’s hot spots.


The heat map of the island shows data from Aug. 31, 2019, the hottest day of the year. Volunteers and city workers placed sensors on their cars and drove specific routes to collect information from neighborhoods across O‘ahu. The 77,456 measurements of temperature and humidity taken went into the map. You can take a look at entire communities or even search specific street addresses to see what the temperature was like in your area at various times of the day.


NOAA measures things by the heat index, which, similar to the wind chill factor, reflects the temperature it feels like outside, as opposed to just the thermometer reading. This takes into account factors such as shaded areas or whether the ground is mostly grass or asphalt. The city says asphalt or concrete can create a swing of as much as 27.7 degrees from morning to afternoon, versus about 8 degrees difference in areas with more trees.


On that record-setting day, the maximum heat index recorded was 107.3 degrees at Waimalu Plaza Shopping Center in Pearl City. Ala Moana, Kāhala, Hawai‘i Kai, Mā‘ili, Nānākuli, Pearlridge and Waimānalo also registered above 105 degrees. The map also shows the heat index above 97.5 degrees stretching from Hawai‘i Kai along the south shore, through Waipahu, continuing from ‘Ewa Beach to Mākaha. The sweltering weather continued, with record-tying or record-breaking temperatures reported on all but four days in September.


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Add to that our disappearing tradewinds—almost a 50% decrease since the 1970s, according to UH professor and state climatologist Pao-Shin Chu—as well as increasing ocean temperatures and there is no question things are getting warmer. So far this year, the National Weather Service reported six days where we tied or broke past record highs in Kahului, Hilo and Honolulu.


Honolulu was 1 of 10 cities that gathered information for heat mapping for the CAPA Heat Watch program, working in partnership with NOAA, other national agencies and universities. The goal is to discover where people are most vulnerable and to help cities decide where to make changes such as planting more trees or increasing green space.


Click here to access the heat map.


Read more about the information gathered in Honolulu’s Heat Watch Report here.