In September the trade winds rattle the coconut palms in the late afternoon, the taro fields of Hanalei shine a hard, wet green, and a line forms at the shave ice stand in Koloa as soon as the schools let out. Summer is winding down on Kauai, but nobody told the water, which is still warm and clear. This is a month for the island’s beaches, canyon lookouts and slow North Shore days, with fewer visitors than July.
What is the weather like in Kauai in September?
Warm and summery, with sunny mornings, a few short showers and trade winds that take the edge off the afternoons.
| Month | Average high (°F) | Average low (°F) | Rain days | Sea (°F) |
|---|---|---|---|---|
| August | 85.2 | 75.2 | 5.3 | 80.0 |
| September | 85.3 | 74.8 | 5.2 | 80.7 |
| October | 83.9 | 73.6 | 5.4 | 81.2 |
Mornings are the best hours of the day. The air is soft, the light is clean, and the mountains often stand clear before clouds gather over the peaks around midday. Afternoons can feel sticky in the sun, especially away from the breeze, so plan the beach, the boat and the hike for the early hours and keep the late afternoon for a shaded lunch or a swim.
Rain comes as quick passing showers, usually a few days in the whole month, and it often arrives with a rainbow behind it. Where you stay matters.
The south and west coasts around Poipu and Waimea stay dry and bright, the east side near Lihue and Kapaa gets the occasional shower, and the North Shore and the mountain slopes are wetter and greener. The summit rim of the canyon at Kokee is much cooler than the coast.
Evenings stay warm enough to eat outside in a T-shirt, with a light layer only for the wind off the water. The days are still long, about twelve hours of daylight in mid-September, so dinner on a lanai at sunset is easy to manage after a full day out.
Can you swim in Kauai in September?
You can swim for an hour in water that is warm enough, no wetsuit needed, and you will not shiver, yes.
Summer patterns usually favor the North Shore, where the big winter swells have mostly gone and bays like Hanalei and Anini tend to be gentler than in January. The south shore at Poipu gets more of its swell in summer, so waves and surf there can be lively. Sheltered spots such as the Poipu Beach Park cove are often easier for children, but the lifeguard and the posted signs decide, not the season.
Snorkelers do best in the morning, when the water is clearest and the wind has not yet picked up. Bring a rash guard, a mask and fins you trust, and mineral sunscreen. Watch the beach flags, ask the lifeguard about currents before you wade in, and keep your distance from sea turtles and monk seals resting on the sand, which are protected. Surfers and nervous swimmers alike should go where a lifeguard is on duty.
What to do in Kauai in September
September has no giant festival, but the month has a local feel. Labor Day weekend sends Kauai families to the beach parks with coolers, tents and ukuleles, and the island’s Hawaiian culture comes forward in the fall with hula, chant and lei-making, including the Mokihana Festival, usually held around September.
If you can catch a hula performance or a craft fair, go. They are the most direct way into the island’s own calendar.
Food this month is simple and good. A plate lunch is easy to track down at a truck by the road, poke waits at a grocery counter, fresh fish turns up in Hanapepe or Kapaa, and shave ice comes with a scoop of ice cream tucked underneath. The island’s farmers markets are lively on weekday mornings, with papayas, apple bananas and pineapple. Pick up lunch there and eat it on a beach.
The Na Pali coast, by sea or by air
Kauai’s signature image is the Na Pali coast, with its green, fluted cliffs, and no road reaches them. Visitors see them from a boat, from a helicopter or a small plane, or from a kayak on a calm day. In summer the sea along this shore is often smoother than in winter, which makes boat trips a good bet, and morning departures tend to be the clearest.
On a boat you slip past sea caves, waterfalls streaming down the walls and, with luck, spinner dolphins riding the bow wave. A helicopter shows you the hidden valleys and the inner crater of Waialeale, the wettest spot on the island.
If you are prone to motion sickness, take the flight, and if you love the water, take the boat. Cancellations are common when the surf or the wind is up, so keep a spare day.
Waimea Canyon and Kokee
On Kauai’s west side, a deep gorge known as Waimea Canyon, or the Grand Canyon of the Pacific, is colored red, orange and green. From the lookouts along the rim you see the layered walls fall away toward the sea, with waterfalls threading down after rain. The road climbs on to Kokee State Park, where the air is cool, the forest is damp and wild chickens strut across the parking lots.
Go early, because clouds often fill the canyon later in the day and hide the colors. September is a good month for it, as the rim is usually less rainy than in winter. Bring a layer, since the top of the canyon is much cooler than the beach where you started. Check the state parks notices page for trail and road conditions before you set out.
Hanalei and the North Shore
Hanalei is a small, laid-back town on a wide, curving bay, with the mountains rising straight behind it and waterfalls running down the green slopes after a shower. You can spend a whole day here wandering the shops, watching surfers paddle out, eating fish tacos and swimming at the bay in the morning. The old pier is the place for photographs at the end of the day.
Nearby, Kilauea has a lighthouse and a wildlife refuge with seabirds wheeling over the cliffs, and the beaches to the east at Anini suit a quieter afternoon. This side of the island is wetter than the south, so a short shower is part of the picture. Pack a light rain jacket and wait it out in a cafe if it hits.
The south shore has its own pleasures. Poipu has long beach days, Spouting Horn blows spray through a lava tube, and Old Koloa Town has old plantation storefronts and ice cream. On the east side, the Wailua River, Opaekaa Falls and the Kapaa bike path are an easy morning, and the Kauai Museum in Lihue is a good stop when it rains.
A two-day itinerary for Kauai in September
Day 1 belongs to the dry south and west. Get to Poipu Beach at first light, while the ocean is still transparent, hardly anyone is on the sand, and the heat has yet to become intense. Swim or snorkel for an hour or two, watch for turtles hauling out on the sand, and then walk to Spouting Horn before the crowds gather. Have a late breakfast in a bakery or coffee stand in Koloa.
By midday, drive up toward Waimea Canyon, stopping at the lookouts and then continuing to Kokee for cool air and a short forest walk. Eat a plate lunch from a roadside stand in Waimea or Hanapepe, where the old bridge and the art galleries make a nice stroll. Come down in the late afternoon for sunset with a drink and a simple dinner at a casual spot near the water.
Day 2 goes north. Leave early for the North Shore and reach Hanalei Bay while the water is still smooth. Swim, paddle or just walk the beach, then browse the town and eat fish tacos or a poke bowl for lunch. If a shower arrives, wait it out in a cafe and then drive on to the lighthouse at Kilauea and the seabird cliffs.
In the late afternoon, head back along the east side. Stop at the Wailua River for the falls, and have dinner in Kapaa, where the restaurants range from food trucks to sit-down places. Rain card: if the weather turns gray, swap the beach for the Kauai Museum in Lihue, the shops and galleries in Hanapepe, or a long lunch in Koloa, then try the beach again in the morning.
Is Kauai busy in September?
Less than in summer and winter, since most mainland schools are back in session and the island has a calmer, local feel.
Labor Day weekend is the busiest stretch, with families, residents and visitors all heading for the beaches and parks. After that the island quiets down, and hotel rooms, rental cars and restaurant tables are easier to find. Many couples, retirees and travelers without school-age children choose this month for just that reason. The beaches in Poipu and Hanalei still have people, but you can find space easily.
For the holiday weekend, book rooms and cars early. For the rest of the month, you can usually plan later, though popular boat trips, helicopter flights and dinners in Hanalei and Poipu still fill up, so reserve those a few days ahead. State park reservations are refunded if the park is closed that day, and the Division of State Parks posts closures on its notices page, which is worth checking before you set out.
What to pack for Kauai in September
Pack light, quick-drying summer clothes and one warm layer for the canyon rim and the evening breeze.
- Pack a thin rain shell for the brief showers that sweep the North Shore and the mountains.
- Reef-safe is not the term to use, so bring mineral sunscreen, which the island’s reefs and rules favor.
- A rash guard and a mask and snorkel, for long mornings in warm water.
- Sturdy sandals or water shoes, for rocky entries and wet trails.
- A fleece or sweatshirt, for the cool air at Kokee.
- A hat and sunglasses, for the strong sun on boats and beaches.
Good to know before you go
The Central Pacific hurricane season runs from June 1 to November 30, so September falls inside it, and it is worth checking the forecast before you fly. In September 2026, Hurricane Lowell passed just west of Kauai on the night of the 7th to 8th, with damaging winds, heavy rain and high surf, damaged roads, trails and parks across the island, and the state closed its lands there while crews cleared them. Check the state parks notices page for the current status of any park or trail you plan to visit.
A rental car is the easiest way around, since the island has few buses and distances are long. Book it early and plan on one coast per day.
| Fee | Amount | Who pays |
|---|---|---|
| State Transient Accommodations Tax | 11.00% | Guests, on the room rate |
| Kauai County Transient Accommodations Tax | 3% | Guests, on the room rate |
| General Excise Tax pass-on, maximum | 4.7120% | Customers, on purchases |
Kauai in September vs August and October
Moving a month earlier means summer in full: school-vacation crowds, fuller beaches and higher demand for rooms and cars. The sea and air are very much the same as in September, so you gain nothing in the weather and lose some of the quiet. Choose August only if your dates are fixed by school.
Moving a month later brings slightly cooler air, a little more rain and a sea that is a touch warmer still. The wetter season is just ahead, with the first winter swells reaching the North Shore later in the fall, and the island stays calm and quiet. The Ironman race in Kona is on another island, but it shows how the fall calendar starts to fill.
If you want the best mix of warm water, dry weather on the south coast and fewer people, stay with September. If school dates or a particular festival tie you to August, go then, and if you prefer a quieter, softer island with lower pressure on rooms and cars, October is a good second choice.
Is September a good time to visit Kauai?
Yes, especially for travelers without school-age children who want warm water, long days and an island that has caught its breath after the summer rush.
Beach lovers, snorkelers, hikers and couples will love it, and so will anyone who likes a local festival more than a crowd. Travelers who need guaranteed sunshine on the North Shore, or who cannot handle a change of plans if a storm or a closure arrives, may prefer another time of year. Hurricane season is in effect, so travel insurance and flexible bookings make sense.
On arrival, spend the first morning at a south-shore beach to settle in and watch the water, then check the state parks notices page before choosing your hikes and drives. September’s own gift is the warm, easy sea, and the feeling that Kauai has gone back to its own rhythm, with hula on a weekend afternoon and a rainbow after the shower.
Sources
- NOAA NCEI, monthly normals 1991-2020, station USW00022536, checked September 8, 2026
- Open-Meteo Marine API, average 2015-2024, checked September 8, 2026
- sunrise-sunset.org, sunrise and sunset calculated for the 15th of the month, checked September 8, 2026
- Hawaii Department of Taxation, Tax Announcement No. 2025-03 (Transient Accommodations Tax Law Changes from 2025 Legislative Session), files.hawaii.gov/tax/news/announce/ann25-03.pdf, checked September 24, 2026
- County of Kauai, Department of Finance, Transient Accommodations Tax page, kauai.gov/Government/Departments-Agencies/Finance/Transient-Accommodations-Tax, checked September 25, 2026
- Hawaii Department of Taxation, County Surcharge on General Excise and Use Tax page, tax.hawaii.gov/geninfo/countysurcharge/, checked September 25, 2026
- NOAA NCEI, monthly normals 1991-2020, station USC00518165
- NOAA NCEI, monthly normals 1991-2020, station USC00513099
- County of Kauai, press release « Hurricane Lowell Update », September 8, 2026, kauai.gov ; DLNR news release of September 16, 2026
- Hawaii DLNR Division of State Parks, dlnr.hawaii.gov/dsp (home page, avis of October 5, 2026)
- NWS Honolulu / Central Pacific Hurricane Center, « 2026 Central Pacific Hurricane Season Outlook », weather.gov/hfo/hurricaneOutlook2026, checked September 24, 2026
To plan your stay
- Things to Do in Kauai: Na Pali Views, Waimea Canyon, North Shore Beaches and Local Food
- Where to Stay in Kauai: Poipu, Princeville, the Coconut Coast and the West Side
- Kauai vs Oahu: Beaches, Things to Do, Weather and Getting Around
- Day Trips from Kauai: Waimea Canyon, Haena and the Na Pali Coast, Wailua and Polihale