Top 5 Cities: Honolulu, Hilo, Kailua, Pearl City, and Waipahu
Hawaii climate data from NOAA Climate at a Glance
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Precipitation, Sunshine, Frost and Snow are converted to standard deviations from their own average so they can share an axis with Temperature anomalies.
Metric
Insight
Temperature
10-Yr AverageActual Year
Climate History
27 of 27 events
1912Volcanic
Novarupta (Katmai) eruption
The largest volcanic eruption anywhere in the world in the 20th century - 13 km3 of magma, about thirty times the 1980 Mount St. Helens eruption - at Novarupta in Alaska on 6-8 June 1912. Ash reached 100,000 ft and cooled the Northern Hemisphere by roughly 0.3°C over 1912-13. Unlike a tropical eruption such as Pinatubo, a high-latitude eruption's haze stays in its own hemisphere, so it did little to the Southern Hemisphere.
After the Second World War, coal and oil use grew rapidly across Europe, North America and the Soviet Union. Global sulphur dioxide emissions rose from about 30 to about 130 million tonnes a year by 1980, and the sulphate haze they formed masked part of the greenhouse warming underneath - the effect known as 'global dimming'.
How much ENSO really controls Hawaii's winter rain
Hawaii has one of the four strongest ENSO rainfall signals in the country and it runs BACKWARDS compared with the southern mainland. Regressing December-February rainfall on the ONI index gives about -16% per index unit, with an r-squared of 0.26: El Niño winters here tend to be DRY, while the same events bring storms to Florida, Texas and New Mexico. Hawaii's wet season depends on trade-wind showers and passing fronts, and El Niño suppresses both. Per-event Hawaii figures are not shown because this site's Hawaii rainfall series does not extend back across the full ENSO record.
The most important dataset in climate science is measured in Hawaii. Charles Keeling began continuous CO2 measurements at Mauna Loa Observatory, high on the Big Island, in 1958, starting at 315 ppm. The site was chosen precisely because it is remote from cities and vegetation, so the air reaching it is well mixed and represents the whole hemisphere rather than anywhere local. That unbroken record is the reason we know the shape of the curve at all.
Agung's aerosol veil is one of only three events that stand out sharply in Mauna Loa Observatory's solar-transmission record, alongside El Chichon in 1982 and Pinatubo in 1991. That record, running continuously on Hawaii's Big Island since 1958, is among the longest direct measurements of atmospheric clarity anywhere - which makes Hawaii one of the places where the climate effect of distant volcanoes is actually observed rather than inferred.
The 1970 Clean Air Act set strict national standards for sulphur dioxide and particulates, and American skies got measurably cleaner over the decades that followed. There is a climate sting in that success: sulphate aerosols reflect sunlight, so removing them removed a cooling effect that had been partly masking greenhouse warming. Hawaii cannot be measured against that comparison: this site's Hawaii temperature series begins in 1991, two decades after the Act, so there is no pre-1970 baseline here to compare with. For the 49 states that do reach back that far, every single one is warmer across 2006-2025 than it was across 1951-1970, by a median of +1.09°C. Hawaii's own warming shows up in its post-1991 record instead: eight of its ten warmest years have come since 2013.
The Pacific Decadal Oscillation is this region's own ocean rhythm rather than a distant one: it is defined by North Pacific sea-surface temperature patterns, and its phase shifts alter trade-wind strength and rainfall across the Hawaiian islands. The 1976-77 flip to a warm phase held for about two decades.
Global sulphur dioxide emissions peak at about 130 million tonnes a year, then begin a long decline as Europe, North America and Japan clean up their air. As the aerosol mask thins, the rate of global warming picks up through the 1980s.
A sulphur-rich eruption in Mexico whose aerosol cloud stayed in the stratosphere for more than two years, cooling the Northern Hemisphere by about 0.2°C.
Hawaii is one of only four states where this site's own data shows a strong winter-rainfall link to ENSO - and it runs the OPPOSITE way to the southern mainland. Regressing December-February rainfall on the ONI index gives Hawaii about -16% per index unit with an r-squared of 0.26: El Niño winters here tend to be DRY, while the same events bring storms to Florida, Texas and California. Hawaii's wet season depends on trade-wind showers and passing fronts, and El Niño tends to suppress both.
The 350 ppm threshold was crossed at Mauna Loa Observatory on Hawaii's Big Island in 1988 - the level James Hansen would later, in 2008, propose as a safe upper limit - and in the same year, 1988, he told a US Senate committee that warming was 'unequivocal'. The measurement that defined the threshold, like every CO2 milestone since, was made here.
Daytime warming catches up with the night-led pattern
Across 1961-90, 81% of the world's land saw nights warming faster than days. Across 1991-2020 the pattern reversed: 70% saw days warming faster, as the industrial haze that had been dimming daytime sunshine was cleaned up. The study compares two fixed thirty-year windows; measured as a turning point, this site's own global series turns around 1982.
Pinatubo erupted in the Philippines in June 1991 and spread an aerosol veil through the tropical stratosphere - the same latitudes as Hawaii. Mauna Loa Observatory has measured direct solar irradiance continuously since 1958, and the sharpest features in that entire record are the transmission drops after Agung in 1963, El Chichon in 1982 and Pinatubo in 1991. Two years on, in July 1993, aerosol optical depth over Mauna Loa was still 0.02 against a background of 0.003. Hawaii did not just experience this eruption - it is where the world measured it.
Atlantic Multidecadal Oscillation flips to a warm phase
The Atlantic Multidecadal Oscillation is, as the name says, an Atlantic cycle. It drives Atlantic hurricane activity and North Atlantic sea temperatures, and has little bearing on Hawaii. The Pacific Decadal Oscillation is the equivalent rhythm for this part of the world.
Hawaii is one of only four states where this site's own data shows a strong winter-rainfall link to ENSO - and it runs the OPPOSITE way to the southern mainland. Regressing December-February rainfall on the ONI index gives Hawaii about -16% per index unit with an r-squared of 0.26: El Niño winters here tend to be DRY, while the same events bring storms to Florida, Texas and California. Hawaii's wet season depends on trade-wind showers and passing fronts, and El Niño tends to suppress both.
Pacific Decadal Oscillation flips back to a cool phase
The Pacific Decadal Oscillation returned to a cool phase around 1998-99. Because the PDO is defined by North Pacific sea-surface temperatures, its phase bears directly on Hawaii's trade winds and rainfall rather than reaching it second-hand.
Start of the sustained rise in US heatwave frequency
Hawaii's own Heatwave Days (WSDI) count - from a separate record that, unlike its temperature series, reaches back to 1950 - rose from a 1961-90 average of 4.8 days a year to 49.0 in 2016-25 - more than a tenfold increase, among the steepest anywhere in the United States.
The 400 ppm threshold was crossed at Mauna Loa Observatory on Hawaii's Big Island on 9 May 2013 - the same instrument record Charles Keeling began there in 1958 at 315 ppm. Every one of these milestones is announced from Hawaii, because that is where the measurement has been made continuously for longer than anywhere else.
8 of Hawaii's ten warmest years in its 1991-2025 record have occurred since 2013, and all ten since 2000, with 2019 the warmest of all - a local acceleration closely tracking the national one.
Hawaii is one of only four states where this site's own data shows a strong winter-rainfall link to ENSO - and it runs the OPPOSITE way to the southern mainland. Regressing December-February rainfall on the ONI index gives Hawaii about -16% per index unit with an r-squared of 0.26: El Niño winters here tend to be DRY, while the same events bring storms to Florida, Texas and California. Hawaii's wet season depends on trade-wind showers and passing fronts, and El Niño tends to suppress both.
Globally, the eleven warmest years on record have all happened since 2015. Hawaii follows closely: eight of its own eleven warmest fall in that span, with 2014, 2004 and 2003 outside. Hawaii's warmest year is 2019.
Dropped 52.02in of rain at one Big Island gauge, breaking Hawaii's all-time tropical-cyclone rainfall record and becoming the 2nd-wettest US tropical cyclone ever (after Harvey). NOAA classified the 4-day, 47.59in total as a 500-year rainfall event.
2019 was Hawaii's warmest year in this site's 1991-2025 temperature record, and it produced 108.6 heatwave days - more than any other state in any other year anywhere in this series. Honolulu and other stations set all-time high-temperature records that summer. For somewhere with famously small seasonal swings, that is a striking departure.
New international shipping rules cut the sulphur allowed in ship fuel from 3.5% to 0.5% almost overnight, removing about 8 million tonnes of sulphur dioxide a year. With less sulphate haze over the oceans, it may have added around 0.1°C of warming by 2023-24.
A strong El Niño arriving on top of long-term greenhouse warming, with the cut in shipping sulphur from the 2020 fuel rule adding a little more. Together they produced the record global temperatures of 2023 and 2024.
The deadliest US wildfire in over a century, following moderate-severe drought and extreme wind (Hurricane Dora's pressure gradient, terrain-amplified).
Source: NOAA Climate at a Glance — US states & climate regions (tavg, pcp), plus GPCC (Snow, water-equivalent). Anomalies are vs the 1961–1990 baseline. See methodology.
Hawaii has a temperate climate (Köppen Cfb: Oceanic / temperate), with little variation in temperature or rainfall across the year. August is typically the warmest month, averaging 21.2°C, while February is the coldest at 17.4°C. Annual precipitation averages around 1557mm (about 86mm of it as snow), spread fairly evenly across the year.
Warmest month
Aug 21°C
Coldest month
Feb 17°C
Annual rainfall
1471mm
Wettest month
Aug 157mm
Annual snowfall
86mmwater-equiv.
Snowiest month
Jan 18mm
RainSnow (water-equivalent)
Monthly climate normals (2016–2025) - bar colour and height show average temperature, the shaded area shows average monthly rain, with snow (water-equivalent) shown separately.
Data: NOAA National Centers for Environmental Information (temperature/precipitation; frost: World Bank CCKP; snow: GPCC (DWD)).
Hawaii is weakly seasonal - temperature barely changes across the year (3.6°C range) and rainfall is fairly even. The clearest climate signal here is overall warming: monthly temperature has risen in every month.
1991–20202016–2025
Baseline vs recent monthly temperature climatology. Biggest warming: Jan (+0.5°C).
Data: NOAA National Centers for Environmental Information (temperature/precipitation; frost: World Bank CCKP; snow: GPCC (DWD)).
Every figure on this page is sourced from official, openly published climate datasets. Anomalies are calculated against the 1961–1990 baseline (temperature) and 1991–2020 (rainfall, sunshine, frost) - see the Methodology & Sources page for the complete dataset list and update calendar.
Hawaii is warming in line with the rest of the world. The page above shows the latest monthly temperature anomaly versus the 1961-1990 baseline, the long-term annual trend, and the region's rank in the historical record. The headline panel also shows the long-term trend rate per decade and the warmest and coolest years on file.
What is the climate like in Hawaii?
Hawaii has a temperate climate (Köppen Cfb: Oceanic / temperate), with little variation in temperature or rainfall across the year. August is typically the warmest month, averaging 21.2°C, while February is the coldest at 17.4°C. Annual precipitation averages around 1557mm (about 86mm of it as snow), spread fairly evenly across the year.
What extreme weather affects Hawaii?
NOAA's Storm Events Database recorded 6 damaging weather events in Hawaii in 2025 - storms, floods, heat, drought and wildfires that killed or injured anyone or did $1M or more of damage - against an average of 5.2 a year in 2016-2025, with 3 deaths. The deadliest since 1996 was the 2023 Maui wildfires (Lahaina) (8 August 2023), which killed 102. GDACS, the UN and European Commission's disaster alert system, issued 0 Major (Red) and 0 Severe (Orange) alerts for Hawaii in the last 12 months. Live alerts are on this page and on the Extreme Weather tracker.
Where does the climate data for Hawaii come from?
Climate data for Hawaii comes from NOAA Climate at a Glance (temperature and precipitation), refreshed every month, when the upstream temperature and rainfall data are refreshed.
What is the climate baseline used on this page?
Anomalies on this page are calculated against the 1961-1990 climatological baseline, which is the standard reference period used by the Met Office, NOAA, IPCC and most national climate services. Some panels also show the source-native 1901-2000 (NOAA) or 1991-2020 (WMO) baselines for verification. See Methodology & Sources for the full reference.
Which areas does the Hawaii climate data cover?
The Hawaii climate profile covers Honolulu, Hilo, Kailua, Pearl City and surrounding areas. Hawaii climate data from NOAA Climate at a Glance
How often is the Hawaii climate update refreshed?
The Hawaii climate update is refreshed monthly, typically a few days after the previous month closes and the upstream provider (Met Office HadUK-Grid, NOAA Climate at a Glance, Copernicus ERA5 or the Global Carbon Project) publishes its update. See the Climate Rankings for cross-region comparisons.
What counts as a Heatwave Day on the Hawaii climate page?
Heatwave Days use the Warm Spell Duration Index (WSDI) - the WMO/ETCCDI-standard heatwave measure: days that are part of a run of 6 or more consecutive days above the local 90th-percentile temperature for that calendar day. The 90th-percentile threshold varies by time of year (a hot day in January is judged differently to one in July) but is fixed to the 1961-1990 baseline for every year shown - it does not shift as the climate warms, which is why Heatwave Days trend upward over time.
Does the Hawaii climate page include frost and snow data?
Yes. Frost Days (days with a minimum temperature below 0°C, World Bank CCKP) and snow water-equivalent (GPCC) are shown alongside temperature and precipitation, each measured against the 1961-1990 baseline where a like-for-like historical comparison is available.
What major climate events has Hawaii experienced?
Major climate events in Hawaii include How much ENSO really controls Hawaii's winter rain (1950-2025); Start of the sustained rise in US heatwave frequency (2010); Post-2013 acceleration in US temperatures; Hurricane Lane's record rainfall, Hawaii (2018); Hawaii's record heat of 2019; The 2023 Maui wildfires (Lahaina). The Climate History panel on this page lists 27 sourced events and pattern shifts relevant to Hawaii, the earliest from 1912 - 6 about Hawaii itself and the rest global context such as volcanic eruptions and El Niño events. Each entry carries its own sources and can be searched, filtered to local events or by category, and sorted by date; scrolling the list moves a cursor across the chart above so you can see where each event falls in the record.
Where does the Climate History list for Hawaii come from, and how is it checked?
It is a hand-reviewed register, not an automatic feed. Every entry is sourced, and each one records how it was verified - against this site's own data series, against a peer-reviewed paper, or against the public record of the event. 16 of the 27 entries here are written specifically about Hawaii, usually quoting its own ranking or measured figures. The rest give global or national context shared with wider pages. Where a figure is narrower than it first appears, or a famous claim does not hold locally, the entry says so.
Are nights warming faster than days in Hawaii?
The Long-Term Trends chart has a Day/Night toggle showing Day Highs and Night Lows anchored around the average trend, so they always bracket it rather than both drifting to one side. Across most of the world, nights warmed faster than days from the 1960s to the late 1980s (air pollution dimming daytime sun), and days have generally been catching back up since, as skies cleared. Toggle Day/Night on the chart above to see which pattern Hawaii follows.
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