Kauaʻi has 6 of the world’s 13 climate sub-zones under the Köppen classification, and 3 of its 5 major zones. The story of the island is interesting: one of the rainiest spots on earth sits a short drive from a coast dry enough for cactus.
Mount Waiʻaleʻale rises near the center and pulls the trade winds straight up. Its summit takes about 350 inches of rain a year, and the wettest ground on the island, just below the summit, tops 390 inches. The same mountain casts a shadow to the west, where Waimea and Kekaha see about 20 inches and the shoreline beyond them reads as semi-arid steppe. Kauaʻi is old and worn low, so it never reaches the cold summits of its taller neighbors. Below, we walk through each of the 6 zones and where you can stand in it.
Table of contents
How many climate zones does Kauaʻi have?
Packing 6 climate zones into about 550 square miles is unusual: most places many times that size never span the same range. The count depends on which system you use, and the most widely used is the Köppen scheme (Wikipedia, or explained in Hydrology and Earth System Sciences). It sorts the planet into 5 major climate zones, splits those into 13 sub-zones, and splits those again into finer groups.
Following the Köppen scheme, Kauaʻi has 3 of the world’s 5 major climate zones and 6 of the 13 sub-zones. It reaches the dry semi-arid step on the west side, which Oʻahu never does, but tops out below the cold summits of Maui and the Big Island.
We marked these zones on the map below. On Kauaʻi the legend colors line up one to one with the Köppen zones, so 6 colors means 6 zones. On the Big Island, where two zones are drawn in two shades each, the map shows 10 colors for 8 zones.
Climate map of Kauaʻi. All 6 legend colors are distinct Köppen zones. The wet interior around Waiʻaleʻale sits a short drive from the dry west coast.
Which climate zones are NOT on Kauaʻi?
Seven of the world’s 13 sub-zones do not reach Kauaʻi. Where one turns up elsewhere in the state, we note it:
- Dry arid, true desert (found on the Big Island)
- Polar tundra (found on Maui and the Big Island)
- Temperate winter dry
- Continental winter dry
- Continental summer dry
- Continental continuously wet
- Polar ice caps
The missing end of the range is the cold one. Kauaʻi’s high point, Kawaikini, reaches 5,243 feet, wet and cool but not cold enough for tundra. That is the twist of the island: it holds one of the wettest places on earth yet no alpine crown, while its drier, taller siblings have both.
How Kauaʻi compares to the other islands
Five zones are on all four main islands: tropical continuously wet, monsoon, tropical dry, temperate summer-dry, and temperate continuously wet. Only three zones separate the islands, and they stack in one order: whatever a smaller island has, the bigger ones have too.
- Big Island, 8 zones: the only true desert in the state, plus tundra on Mauna Kea and Mauna Loa.
- Maui, 7 zones: tundra on Haleakalā and steppe at Kīhei, but no desert.
- Kauaʻi, 6 zones: steppe on the west coast, and no summit high enough for tundra.
- Oʻahu, 5 zones: the narrowest range of the four. No steppe, no desert, no tundra.
The climate zones of all Hawaiian islands on one map. The state spans 8 of the world’s 13 zones, and every one of them is found on the Big Island.
If you are working out when to come rather than where to stand, we cover that separately in the best time to visit Kauaʻi.
The 6 Kauaʻi climate zones, region by region
Here is each climate you can find on Kauaʻi, grouped by major family, with the sub-zones that appear and where to stand in each.
Humid Tropical climate
In these climates every month averages warmer than 64° F (18° C) and rain is plentiful. All three tropical sub-zones appear on Kauaʻi, sorted by how the rain falls across the year.
Continuously wet
No real dry season. Rain all year. This is the largest zone on the island, about 44% of it: the flanks of the wet interior, the whole north shore, and most of the east. Color on the map
Where to find it on Kauaʻi: the slopes of Mount Waiʻaleʻale below the summit, the north shore around Hanalei, Princeville, Kīlauea and Hāʻena, the cliff-top rim above the Nāpali Coast, and the east side around Līhuʻe, which takes about 50 inches of rain a year.
The north shore has no dry season worth the name: every month here is a wet month. Encircled by waterfall-draped mountains, the picturesque Hanalei Valley on the north shore of Kaua‘i harbors the Hanalei National Wildlife Refuge. Image by Jason Weingardt on Unsplash
Monsoon
A short dry season, but enough rain the rest of the year to keep the ground wet. On Kauaʻi it is the thinnest zone, about 2% of the island, ringing the wetter ground as a transition band. Color on the map
Where to find it on Kauaʻi: the coastal strip on the east side around Kapaʻa and Anahola, and thin bands on the windward slopes just outside the wettest interior.
Anahola sits in the island’s narrow monsoon band, on the east coast. A windy sunrise at Anahola Beach. Image credit: Twelvizm, source.
Dry
A clear dry season, here in the summer. This is the second largest zone, about a quarter of the island, covering the south coast and the low country on the west. Color on the map
Where to find it on Kauaʻi: the sunny south coast at Poʻipū, which takes about 37 inches of rain a year, Kōloa and Hanapēpē, and the west-side towns of Waimea and Kekaha, plus the low mouth of Waimea Canyon and the beach at Polihale. The west side is dry, around 20 inches a year, but it keeps a wet enough winter to stay tropical rather than tip into steppe.
Poʻipū, on the dry-summer south coast, takes about 37 inches of rain a year. Poipu is a popular beach with a shallow, protected swimming area, snorkel & surfboard rentals & a playground. Image: Hawaii Tourism Authority (HTA) / Tor Johnson
Dry (arid and semi-arid) climate
In this climate the yearly evaporation outpaces the rainfall. Kauaʻi reaches the semi-arid step but never crosses into true desert.
Dry semi-arid (steppe)
A dry grassland climate, drier than the tropics but wetter than desert. This is the smallest zone on Kauaʻi, about 1% of the island, and it is easy to miss: a narrow shoreline strip, not a region. Color on the map
Where to find it on Kauaʻi: the coast running northwest from Kekaha beach past Barking Sands and along the Mānā plain, the driest ground on the island at about 18 inches a year, deep in Waiʻaleʻale’s rain shadow. Step half a mile inland and you are back in the tropical dry zone.
Polihale sits at the north end of the dry west coast, just beyond the steppe strip. Polihale State Park is a remote wild beach and a great choice for those people seeking isolation. Image credit: K E V I N, source.
Temperate climate
The coldest month averages between 27° F (-3° C) and 64° F (18° C), and the warmest month is above 50° F (10° C). Two sub-zones appear on Kauaʻi, both in the uplands.
Continuously wet
At least 30 mm of rain in the driest month, with a smaller swing between wet and dry. This is the cool wet heart of the island, and it is bigger than most visitors expect: about a quarter of Kauaʻi. Color on the map
Where to find it on Kauaʻi: the high interior around the summits of Waiʻaleʻale and Kawaikini, most of which has no road to it, and the part you can drive to, Kōkeʻe at around 3,600 to 4,000 feet, where the air runs 10 to 15° F cooler than the coast and nights drop into the 40s.
Summer dry
At least three times as much rain in the wettest winter month as in the driest summer month. A warm dry-summer pocket on the drier upland rim. Color on the map
Where to find it on Kauaʻi: the ridges along the western rim of the canyon, including the ground around the main lookouts.
The canyon’s western rim is cool enough to count as temperate, and dry enough in summer to sit apart from Kōkeʻe up the road. Waimea Canyon State Park is also know as the known as the “Grand Canyon of the Pacific” for obvjous reasons. Image credit: Trogers on Flickr.
How we counted the zones
The count of 6 sub-zones on Kauaʻi uses the most common form of the Köppen classification, the same one we use across this series. Köppen is a 3-tier system: 5 main climates in the first tier, splitting into 13 sub-zones in the second, and into 28 or 30 finer groups in the third. When we say Kauaʻi has 6 of the world’s 13, we mean the second tier.
On Kauaʻi the map’s colors match the Köppen zones one for one, so counting the colors gives the right answer. On the Big Island that is not the case, because two zones are drawn in two shades each, which is how that map ends up with 10 colors for 8 zones.
Our zones are computed from the University of Hawaiʻi Rainfall Atlas (Giambelluca et al. 2013) and Evapotranspiration Atlas (Giambelluca et al. 2014) at 250 m resolution. We feed the monthly rainfall and temperature for every 250 m pixel through the standard Köppen decision rules set out by Peel, Finlayson, and McMahon (2007). That resolution is what holds the steppe strip on the west coast apart from the tropical dry country right behind it, which a coarser map would average into one.
The base period is 1978 to 2007. Climate zones are built on 30-year normals, so they barely shift between one recent period and the next. What sharpens the map is resolution, not which decade you average.
For where these zones actually put you on the ground, see our guides to Kauaʻi’s sights and destinations and Kauaʻi’s waterfalls.