What Is The Temperature In Hawaii?

With its tropical climate and sunny days throughout the year, Hawaii is known for its warm, pleasant weather. If you’re wondering what the temperature is like on the Hawaiian islands, here’s a quick overview: the average year-round temperature is around 80 degrees Fahrenheit.

In this comprehensive guide, we’ll be diving deep into Hawaii’s temperatures. We’ll take a look at the average temperatures on the different islands, how much temperatures vary between winter and summer, historical temperature trends, and how elevation and rainfall impacts temperatures across the state.

Average Temperatures on the Hawaiian Islands

Oahu Temperatures

Oahu enjoys warm temperatures year-round, with an average high of 85°F in the summer and an average high of 80°F in the winter. The weather is fairly consistent, with only about a 5 degree difference between the coolest and warmest months.

Oahu does get more rain in the winter months between October and April.

Maui Temperatures

Maui has very similar weather to Oahu, with warm temperatures year-round. In the summer, highs average 85°F while winter highs are around 79°F. As with all the islands, Maui can experience passing rain showers at times, especially on the northern and eastern sides of the island which tend to be rainier.

The leeward sides of islands tend to be drier.

Hawaii Island Temperatures

The Big Island has the most diverse climate in Hawaii, with very different weather on each side of the island. The Kona side has abundant sunshine and very little rain, with average highs of 87°F in summer and 83°F in winter.

Meanwhile, the Hilo side gets over 120 inches of rain per year and has cooler highs averaging 81-83°F year-round. Up on Mauna Kea volcano, freezing temperatures and snowfall can occur during winter!

Kauai Temperatures

Known as the Garden Isle for its lush greenery, Kauai has an average year-round temperature of 78°F. Summer highs reach up to 87°F while winter highs are around 82°F. As one of the wettest spots on Earth, Mount Waialeale in Kauai’s interior sees about 450 inches of rainfall annually!

So while temperatures remain warm and consistent, Kauai does get quite a bit of rain.

Seasonal Temperature Variation

Winter Temperatures

Hawaii enjoys warm and pleasant temperatures all year round, but there is some seasonal variation. During the winter months from December through February, average highs are typically in the low 80s Fahrenheit along the coasts and in the mid 70s Fahrenheit at higher elevations.

Low temperatures only drop into the mid to upper 60s overnight. The cooler winter months bring more rainfall, but temperatures remain very comfortable for beachgoing and outdoor activities.

Summer Temperatures

Summers in Hawaii, spanning June through August, are considered hot and dry. High temperatures reach the upper 80s on average along the coasts with low 90s common inland and at lower elevations. The warmest months see average highs approaching 90 degrees Fahrenheit.

Overnight lows only fall to around 70 degrees even during the hottest weather. While humidity can cause summer heat to feel oppressive at times, gentle trade winds flowing down from the mountains typically keep things quite comfortable during the daytime hours.

Historic Temperature Trends in Hawaii

The temperatures in Hawaii have been relatively stable over the past century, with only slight upward and downward trends. According to data from the National Oceanic and Atmospheric Administration (NOAA), the average temperature in Hawaii has increased by about 1.3°F since the early 1900s.

There are a few key factors that influence Hawaii’s temperatures:

• Proximity to the ocean – The Pacific Ocean has a moderating effect on air temperatures, keeping them relatively stable throughout the year.
• Elevation – Temperatures tend to decrease by about 3.5°F for every 1,000 feet of elevation gain. The higher inland mountain areas are generally cooler.
• Trade winds – The persistent northeasterly trade winds help circulate air and limit daytime heating and nighttime cooling.

The hottest months in Hawaii are typically August and September, right before the winter rainy season begins. The coolest months are January and February. However, the difference between the warmest and coolest monthly average temperatures is only about 6°F along the coasts.

Climate change has started impacting temperatures in the Hawaiian Islands, though less severely compared to other places globally. Since the 1950s, nighttime low temperatures have risen more rapidly than daytime highs.

Going forward, climate models project that Hawaii could warm by 2-4°F by the mid to latter half of this century if global emissions are not curbed (source). This highlights the importance of reducing carbon emissions worldwide to limit future temperature rise.

Impact of Elevation and Rainfall on Temperatures

Higher Elevations are Cooler

As one ascends in elevation, temperatures generally become cooler in Hawaii. For every 1,000 feet gained, the temperature decreases by approximately 3-5°F on average. This relationship between elevation and temperature is largely due to adiabatic cooling, which describes how air expands and subsequently cools as it rises in altitude.

Therefore, higher elevations and mountain peaks across the Hawaiian Islands experience markedly cooler temperatures than coastal areas. For example, the summit of Mauna Kea on Hawaii Island has an average annual temperature around 40°F, while Hilo on the windward coast averages 73°F annually.

The elevation difference between these two locations is nearly 14,000 feet!

Rainfall Cools Things Down

Increased cloud cover and rainfall also promote cooler than average conditions across Hawaii. When moisture-laden trade winds hit high terrain, the air is forced upward and cooled, often resulting in cloud formation and precipitation on windward mountain slopes.

For instance, Mount Waiʻaleʻale on Kauai has an average annual rainfall exceeding 450 inches. These incredible amounts of precipitation on the summit help suppress daytime highs to around 65°F annually.

Meanwhile, leeward Kauai locales in the rain shadow of Mount Waiʻaleʻale average highs around 85°F.

The cooling effect of clouds and rain can be very noticeable even in lower elevations. During prolonged heavy rainfall, daytime highs may only reach 75-80°F in places that normally see summer temperatures in the 90s.

So next time a rainy day keeps things cooler than normal, you can thank adiabatic cooling processes and the precipitation itself for literally dampening the heat!

Conclusion

To sum up the key takeaways: Hawaii enjoys warm tropical temperatures year-round, averaging around 80°F. While winters are a few degrees cooler than summers, the temperature variation throughout the year is relatively minimal thanks to Hawaii’s subtropical climate.

Historic trends show temperatures in Hawaii have been slowly rising over the past century. And finally, temperatures can fluctuate across the islands and even within the same island based on elevation, rainfall, and positioning to trade winds.

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