Poʻipū on Kauaʻi’s south shore averages 37 inches of rain a year. Princeville on the north shore averages 75. The west side past Waimea gets about 20. All three sit on one island of 550 square miles, and the average temperature between them differs by barely more than a degree.
Where you sleep decides your weather far more than the month you fly in. The north and east shores face the incoming trade winds and stay green year round. The south shore is sunnier and drier, and the strip past Waimea is Kauaʻi’s near-desert. The island fits 6 of the world’s 13 climate zones into that footprint. Pick your shore first, then your month.
Table of contents
What is the best time to visit Kauaʻi?
For the south shore, any month: Poʻipū stays dry and warm year round. Winter changes the north shore instead: Nāpali Coast boat tours run from the south side and Hanalei takes its heaviest rain. Humpback whales arrive in those same months. Our full guide to the best time to visit Kauaʻi weighs all of it month by month. Hurricane season, June through November, is covered on our Hawaiʻi weather page.
Kauaʻi at a glance
The whole Kauaʻi year in one card, shore and calendar together.
Month by month: temperature, rainfall, and cloud
Kauaʻi has two seasons, and neither is cold. Winter, roughly October through April, brings more rain and bigger surf on the north shore. Days run slightly cooler. Summer, May through September, is drier and warmer, and the trade winds blow more reliably. The island-wide average daytime high moves from 74.7 F in February to 80.4 F in September, a swing of under six degrees.
So read “winter” here as a rain-and-surf season, not a temperature season. A February beach day in Poʻipū feels close to an August one. The difference shows on the north shore: Hanalei Bay is calm enough for paddling in August, and the same bay carries serious surf in January.
Temperatures stay in a narrow band
At Līhuʻe Airport the average daily high runs from 78.1 F in February to 85.3 F in September, and nights range from 66.0 F in January to 75.2 F in August. Princeville’s afternoons keep up, peaking at 85.9 F in August, but its nights run cooler all year, down to an average 62.3 F in January. Pack one light layer for winter evenings on the north shore; nothing else in the table asks for more than shorts weather.
| Month | Līhuʻe high / low | Princeville high / low |
|---|---|---|
| January | 79 / 66 | 78 / 62 |
| February | 78 / 66 | 77 / 63 |
| March | 79 / 67 | 77 / 63 |
| April | 80 / 70 | 80 / 65 |
| May | 82 / 71 | 83 / 67 |
| June | 83 / 73 | 84 / 68 |
| July | 85 / 75 | 85 / 69 |
| August | 85 / 75 | 86 / 70 |
| September | 85 / 75 | 85 / 70 |
| October | 84 / 74 | 83 / 68 |
| November | 81 / 71 | 80 / 67 |
| December | 79 / 69 | 78 / 65 |
| Average daily high and low in °F, NOAA 1991-2020 normals. Līhuʻe is Līhuʻe Airport (USW00022536), Princeville is Princeville Ranch (USC00518165). These are monthly averages, not records: a warm afternoon runs above the high, a cool night below the low. | ||
The interior runs cooler than the coast in every month. January and February are the coolest, at an island-wide average daytime high of 74.7 F; September is the warmest at 80.4, with August right behind at 80.0. Those figures average in the cool interior, so the shore runs warmer than the map suggests: Līhuʻe’s September normal high is 85.3 F. On Kauaʻi, elevation changes the temperature far more than the calendar does, and every beach sits at the warm end of the scale in every month.
Average daytime high for each month, on one color scale for the whole year. February averages 74.7 F across the island, September 80.4 F. Data: Giambelluca et al. (2014), 250 m grid. Map by Love Big Island.
Rainfall is where the seasons show
November is the wettest month island-wide at 9.3 inches, with December and March close behind at 8.6 and 8.5. June is the driest at 5.1. The split is clean: every month from October through April clears 6.7 inches, and no month from May through September reaches 6. October is the hinge, at 7.1 inches the first month since April to cross that line.
These are averages over the whole island, soaked interior included, so an island-wide 9.3-inch November overstates what any single shore gets. Most of that rain falls on the mountains and the north and east sides. The table below samples a single town on each shore, wettest to driest.
| Place | in / yr | mm / yr | Setting |
|---|---|---|---|
| Hanalei | 81 | 2,060 | North shore bay |
| Princeville | 75 | 1,910 | North shore, wet |
| Kōloa | 57 | 1,460 | South, inland of Poʻipū |
| Wailua | 46 | 1,180 | East, river mouth |
| Līhuʻe | 45 | 1,140 | East, the airport town |
| Kapaʻa | 42 | 1,060 | East, the Coconut Coast |
| Poʻipū | 37 | 940 | South shore, sunny |
| Waimea | 20 | 520 | West coast, dry |
| Kekaha | 19 | 490 | West coast, driest town |
Winter rain and winter surf arrive together, and both hit the north shore first. Nāpali Coast boat tours move their departures to the island’s south side for the winter because the north-facing swell makes the run too rough. Hanalei takes its heaviest rain in those same months, while Poʻipū, in the lee of the mountains, keeps most of its sun.
Average rainfall for each month, draped over the island’s terrain. Every month uses the same color scale, so a wet month and a dry month can be compared directly. November averages 9.3 inches across the island, June 5.1. Data: Rainfall Atlas of Hawaiʻi (Giambelluca et al. 2013), 250 m grid. Map by Love Big Island.
Sunny skies and cloud cover on Kauaʻi
March is the cloudiest month, with cloud over the island for 64 percent of daylight hours on average, and it is one of the wettest at 8.5 inches. September is the clearest at 46 percent and pairs that with the year’s warmest afternoons. If your dates are flexible, September is the strongest weather bet Kauaʻi has.
Cloud doesn’t track rain exactly. The atlas grid puts Līhuʻe under cloud 57 percent of daylight hours against Princeville’s 49, even though Princeville gets 30 more inches of rain a year. Poʻipū sits at 42 percent, the sunniest of the three, which is why the same afternoon can be gray in Līhuʻe and clear over the Poʻipū beaches.
Book the south shore if the trip is built around beach and pool days. Its 42 percent cloud and 37 inches of rain are as sunny as this island gets, short of driving out to Waimea.
Average cloud cover during daylight hours for each month, on one color scale. March is the cloudiest month at 64 percent island-wide, September the clearest at 46. Data: Giambelluca et al. (2014), 250 m grid. Map by Love Big Island.
How the trade winds shape local weather
The trade winds arrive from the northeast on 80 to 95 percent of days from May through September, and on 50 to 80 percent of days from October through April, per NOAA’s climatography. On most high islands the moist air climbs the windward slope, cools, and drops its rain there. On Kauaʻi the trades largely wrap around the Waiʻaleʻale massif rather than climbing over it, so the wet-dry line curls around the island instead of cutting it in half. Princeville and Poʻipū make the cleanest pair: the same ocean, one ridge of mountains apart.
The windward side catches the rain
Princeville and the north and east shores face the incoming trades. The air rises over the mountains, cools, and drops its rain on the way: Princeville averages 75.3 inches a year, and Līhuʻe on the east side 45.1. Both stay green year round, and both take their heaviest rain in winter.
Princeville, the wet shore: 75.3 inches of rain a year under 49 percent daytime cloud. Shown on the same rainfall scale as the Poʻipū chart below, so the wet-dry gap is plain. Data: Giambelluca et al. (2013, 2014), 250 m grid. Chart by Love Big Island.
The leeward side sits in the rain shadow
Poʻipū sits around the corner in the lee and gets 37.0 inches a year; past Waimea the annual total drops to about 20. Mean temperatures across all these points sit within 1.3 degrees of each other, so position in the wind, not warmth, is what separates the shores. A wet morning at an east-side hotel still leaves you a dry afternoon out west: the deepest lee is toward Waimea, a drive into drier weather almost any day the trades blow.
The exception is Kona wind. When a winter front breaks down the trades, the wind swings to the southwest and the pattern flips: rain reaches Poʻipū and the west side while the north shore gets a break. Expect that mostly between October and April.
Poʻipū, the dry shore: 37.0 inches of rain a year under 42 percent daytime cloud, on the same rainfall scale as the Princeville chart above so the wet-dry gap is plain. Data: Giambelluca et al. (2013, 2014), 250 m grid. Chart by Love Big Island.
Beach days and ocean conditions
Kauaʻi’s south and west shores give you the most beach days, dry and bright most of the year, while the north and east shores catch the trade showers that keep them green. The water stays warm all year, from about 74°F in late winter to 80°F by early fall. High surf and brown water can both spoil a swim on an otherwise sunny day, and neither shows up in a weather forecast.
Beach days
Kauaʻi’s beach weather changes more from shore to shore than from day to day. Which shore you pick decides your odds of a clear afternoon. Here’s how eleven of its beaches rate.
A beach-weather rating for eleven Kauaʻi beaches, deep blue for the best. Each card marks the beach's score out of 100, the month it's at its best, how cloudy a typical day runs hour by hour, and the clearest hours in orange. Data: UH rainfall and cloud atlases, 250 m. Map by Love Big Island.
The west and south shores carry the best beach weather: Polihale and Kekaha out west, Poʻipū and Gillin’s in the south, all dry and often clear. The east-shore beaches around Līhuʻe and Kapaʻa rate in the middle, greener and cloudier. The north-shore beaches, Hanalei and Tunnels and Keʻe, are the wettest on the island, and all that rain is why the north shore stays green. The clearest hours come in the morning on the west and south shores, early afternoon on the windward east and north.
How we rate the beach days
We rate each beach on how many good beach hours you can count on. Two things set the score: how much rain falls and how cloudy the sky is, averaged month by month over thirty years. The scores are relative, comparing these beaches with each other rather than promising sun on any day: a higher one means more dry, bright days over the year. The best month is the month that scores highest, when both rain and cloud bottom out. The clearest hours come from a separate record of how cloudy it gets hour by hour through a typical day, so it tells you the best time to be on the sand: mornings on the west and south shores, early afternoon on the windward side. Use the score to compare beaches, the best month to time each one, and the clearest hours for when to head down.
Brown water
Brown water is what runs off the land after heavy rain: storm runoff carrying pathogens from cesspools and septic tanks, animal waste from storm drains, sewage from overflowing manholes, and chemicals from paved runoff. It turns the nearshore water murky and brown, and Kauaʻi is named in the state’s advisory. The island’s north shore saw one of the heaviest single-day rainfalls ever recorded in the United States in April 2018, and brown water can follow any hard rain. The rule is simple: stay out of brown water, and out of the streams feeding it, until it clears. The Hawaiʻi Department of Health sets no waiting period, so do not trust the common 48-hour figure; that number belongs to sewage and chemical spills, not storm water. Let the department, not a clock, tell you the water is clear. Check the Clean Water Branch’s map of current beach advisories for what’s posted where you’re staying.
Surf
Big surf runs on a different calendar than the weather, so a calm, sunny week can still bring a rough ocean. The north shore sees the year’s largest swells in winter, when Hanalei Bay and the Nāpali coast turn dangerous and the boat tours shift to the south side; south-facing shores get their turn in summer. A dry, sunny January week can still put heavy surf on the north shore, so check the National Weather Service Hawaiʻi surf zone forecast for the specific shore you’re swimming off before you go in.
Waiʻaleʻale, among the wettest places on Earth
Waiʻaleʻale rises 5,148 feet at the center of the island, and the rain gauge near its summit has long averaged over 370 inches of rain a year. That is ten times the rain that falls on Poʻipū, on the same small island. You will see it called the wettest spot on Earth: that title rests on a 1980s figure of 486 inches that modern gauges have not matched, but it remains one of the two or three wettest places ever measured, and among the best-measured. A 2013 study by Ferrier and colleagues found that Kauaʻi packs more than 70 percent of the range of rainfall rates found anywhere on Earth into 25 kilometers of ground.
All of that water drains outward and feeds the island’s rivers and waterfalls. The summit sits socked in most days, and visitors almost never see it clear.
Plan around the shores instead. The rain up there keeps the rivers running and the north shore green; Poʻipū gets 37 inches a year on an island whose center catches 370. Pick the shore that matches your trip. The sun stays in Poʻipū either way.
Sources and methods
- Temperature normals and the monthly high/low table: NOAA 1991–2020 station normals, Līhuʻe Airport and Princeville Ranch.
- Rainfall maps and the town rainfall table: UH Rainfall Atlas of Hawaiʻi (Giambelluca et al. 2013), 250 m grid, 1978–2007.
- Temperature and cloud maps, and the Princeville and Poʻipū climate charts: UH Evapotranspiration Atlas (Giambelluca et al. 2014), 250 m grid.
- Beach-weather map: the same UH rainfall and cloud atlases, 250 m. A relative, typical-conditions rating, not a forecast and not a count of good days.
- Trade-wind frequencies: NOAA climatography of Kauaʻi.
- Rainfall gradient across the island: Ferrier et al. (2013), Geological Society of America Bulletin.
- Brown-water advisories: Hawaiʻi Department of Health, Clean Water Branch.
- Surf: National Weather Service Honolulu surf zone forecast.