What to look for in nature in Hawaii this October

Most of them are already here. The kōlea, or Pacific golden-plover, nests on the tundra of Siberia and western Alaska and spends roughly nine months of every year in the islands. DLNR’s species account says most adults land in August and the juveniles in October, with the spring departure starting in late April. Hawaii is thought to hold a large share of the world’s wintering kōlea.

The Hawaiʻi Audubon Society’s Kōlea Count has sharpened those dates with reports from backyards and parks. In 2026 the first six birds turned up at Kealia Pond National Wildlife Refuge on Maui on July 1, still in partial breeding dress, and 64 were reported back before July was out. Their tracking figures put the one-way trip at about 3,000 miles, flown nonstop in three to four days. Females come first, males follow in mid-to-late August, and the summer’s young arrive in October and November, depending on Arctic weather, with no breeding color at all.

Hawaii’s native shearwaters and petrels nest in burrows high in the mountains and fly to sea at night. Their chicks make that first flight in fall, and bright artificial lights confuse them: they circle streetlights, stadium lights and hotel grounds until exhausted, then land and cannot easily take off again. Kauaʻi County gives the fledgling season as September 15 to December 15. DLNR calls October the peak month for young ʻaʻo, the Newell’s shearwater, to leave their burrows, and the Kauaʻi Endangered Seabird Recovery Project notes that groundings get worse on dark nights, near a new moon or under heavy cloud. This year the new moon falls on October 10.

The stakes are high. Surveys by that project found Kauaʻi’s ʻaʻo population fell 94 percent between 1993 and 2013, and the ʻuaʻu, or Hawaiian petrel, 78 percent.

The ocean around Hawaii changes sides in fall. The University of Hawaiʻi Sea Level Center’s surf climatology gives the North Shore of Oʻahu an active season from September to May, when face heights average about 12 feet with a spread of eight feet either way, and the south shore an active season from March to October, now winding down. The state’s ocean safety office describes the same flip: calm north and west shores in summer, then dangerous, consistent high surf there from late fall through winter while south shores flatten. The first long-period north-northwest swells of the year can arrive in October, and they reach beaches that looked like lakes a month earlier.

The sea itself is at its warmest of the year, about 79 to 80 °F around late September and early October, according to the Western Regional Climate Center.

A note on box jellyfish: along Oʻahu’s leeward and south shores they arrive in a monthly cycle tied to the full moon. The Waikīkī Aquarium publishes estimated arrival dates; lifeguard signs on the day are the final word.

Hawaii’s forest birds are the state’s quiet emergency. DLNR counts 84 forest bird species known from the islands, of which 28 vanished before written records and 30 more are extinct or presumed so, leaving 26 alive today; 24 of those carry an IUCN threat category. Most survive only in high forest above the reach of the mosquitoes that spread avian malaria. The Birds, Not Mosquitoes partnership is now releasing mosquitoes carrying a natural Wolbachia bacterium on Maui and Kauaʻi, which work as mosquito birth control, to buy the honeycreepers time.

Wherever you walk in native forest, the University of Hawaiʻi’s Rapid ʻŌhiʻa Death guidance applies: brush the soil off boots and gear before and after, spray them with 70 percent rubbing alcohol, wash clothes in hot soapy water, and never move ʻōhiʻa wood.

At the end of September, yes, in pulses. The summit eruption inside Halemaʻumaʻu crater that began in December 2024 has gone on as a long series of short fountaining episodes separated by quiet spells. On September 29 the USGS Hawaiian Volcano Observatory kept Kīlauea at alert level WATCH, aviation code ORANGE, and reported strong glow and spatter from the north and south vents, repeated overflows and drainback, and summit inflation, with episode 55 fountaining “a possibility.” No unusual activity was reported outside the summit.

This month. Hawaiians recognized two seasons, Kau from May through October and Hoʻoilo from November through April. The Western Regional Climate Center’s Hawaii narrative says modern records support a slightly different split: a seven-month winter from October through April and a five-month summer from May through September. In summer the trades blow 80 to 95 percent of the time; from October on that falls to 50 to 80 percent, and the gaps are filled by Kona lows, cold fronts and upper-level troughs that can rain on the leeward side too. Major storms are most frequent from October through March.

You can see the turn in the normals. Honolulu’s rain jumps from 0.88 inch in September to 1.51 in October, Kahului’s nearly doubles, and even arid Kona picks up. On the windward side the numbers are of another order: Hilo averages more than 10 inches in October, and 14 in November.

The one Hawaii station with a freeze normal in the site’s NOAA data is that last one, Mauna Loa 5 NNE, at the Mauna Loa Observatory: its first fall freeze comes by November 9 one year in ten, by December 1 in a median year, and by January 7 nine years in ten. The summits of Maunakea and Haleakalā go below freezing on many winter nights and can see snow; sea level never has.

This year’s hurricane season has already been the story of the fall. Hurricane Lala brought flooding rain in mid-August, and the Honolulu forecast office wrote that many gauges got nearly their whole month’s total in a day or two. Hurricane Lowell battered Kauaʻi in the first week of September, and DLNR closed its lands on the island afterward. On September 30, Tropical Storm Nolo was still turning near French Frigate Shoals in Papahānaumokuākea. The central Pacific season runs through November 30, so keep an eye on the Central Pacific Hurricane Center.

Most likely, a dry one. Forecasters at the Climate Prediction Center wrote on September 10 that an exceptionally strong event is now better than a nine-in-ten bet for the coming cool season. In the islands the usual signature is the reverse of what many mainland readers expect: NOAA’s Pacific ENSO Applications Climate Center summarizes it as more rain early in the wet season, then rapidly less, with weaker trades, occasional westerly winds, tropical storms forming closer to the islands, and bigger surf from distant storms. NOAA’s Climate.gov puts the typical El Niño winter at about three inches below normal in Honolulu, whose yearly total is only around 16 inches at the airport.

The CPC’s own Hawaii outlook, issued September 17, already leans that way: a 60 percent chance of below-normal rain at Hilo, Kahului, Honolulu and Līhuʻe for October through December, rising to 70 percent for November through January and 75 percent for December through February, with warmer than normal odds this October. October itself is the part of the season least changed by El Niño, and may still bring a big rain or two. The drying tends to show from November, and a short wet season leaves dry grass and brush that can feed wildfires by the following spring. NOAA’s updated winter outlook is due in mid-October.

Little more than half an hour, the smallest loss in the country. Hawaii sits between 19° and 22° north, so days here never stretch or shrink as far as they do on the mainland. Līhuʻe gives up 36 minutes over the month and Hilo and Kona 32, a little over a minute a day. In Honolulu the sun rises at 6:23 a.m. on October 1 and 6:34 on October 31, and sets at 6:19 p.m. and 5:56 p.m. Hawaii keeps Hawaii Standard Time all year, so when the mainland falls back on November 1, nothing changes here except the gap to the mainland, which shrinks by an hour.

Drop a pin on your own valley or beach in the Field almanac to get its first light, last light and day length.

The islands have some of the best skies on Earth, and the summits of Maunakea and Haleakalā sit above most of the clouds. Times below are Hawaii Standard Time; Hawaii has no daylight time to end.

Watch the Pleiades, Makaliʻi, rising a little earlier each evening; by mid-November they come up in the east at dusk, the traditional sign that the Makahiki season has arrived. Before a night drive up the mountain, see whether the trade-wind clouds will clear on our Today’s sky forecast, and look up tonight’s moonrise for your island with the moon phase calendar.

1. Log your kōlea. Report its arrival to the Kōlea Count by November 30, and sign up for a winter Little Count of your own yard or school field. Watch for the plain young birds that turn up this month.
2. Go on a Forest Bird Hike at Hosmer Grove in Haleakalā National Park on October 13, 14, 27 or 28, 9–10 a.m., free, led by a park biologist. On Friday, October 2, the park’s Nēnē Awareness Day pop-up on the Headquarters Visitor Center lawn (10 a.m. to 2 p.m.) has games, crafts and the biologists who look after the geese.
3. Pull weeds for the rainforest. Hawaiʻi Volcanoes National Park’s Stewardship at the Summit volunteer mornings are on the park calendar for October 3, 17, 24 and 31, meeting at 8:45 a.m. in the Kīlauea Visitor Center parking lot; gloves and tools are provided, and volunteers under 18 need a parent or guardian with written consent. Confirm first; the event text still shows summer dates. On Oʻahu, Waimea Valley’s Make a Difference Day on Saturday, October 24, 9 to 11:30 a.m., needs volunteers for weeding and invasive-plant removal.
4. Walk under the full moon. Waimea Valley’s October Moonwalk, the last of the season, is Sunday, October 25, 8 to 10 p.m., by ticket, on the night of the Hunter’s Moon.
5. Hunt for a happy-face spider. On Saturday, October 31, rangers lead a Spooky Scavenger Hunt near the Kīlauea summit from noon to 4 p.m., starting at the flagpole in front of the Kīlauea Military Camp Welcome Center, and the Kahuku Unit runs its Halloween Bingo Scavenger Hunt from 9 a.m. to 3 p.m. Costumes encouraged.
6. Use the fee-free day. Tuesday, October 27, Theodore Roosevelt’s birthday, is free entry at all fee-charging national parks, including Haleakalā and Hawaiʻi Volcanoes.
7. Keep a rain gauge. A straight-sided jar and a ruler will do. Record the first big wet-season rain, compare it with the normals in the table above, and when a Kona low is forecast, watch the barometer fall on our Weather now readout.

Coming next: Waimea Valley gives away trees for Arbor Day on Saturday, November 7, and holds its Makahiki Festival on Wednesday, November 11. The Naturalist’s Field Journal has plates for all of this, and the nature pages for other months and places are collected in one index.

• Kauaʻi after Hurricane Lowell. Most DLNR lands on the island were still closed in late September. The limited reopening on September 21 covered Wailua River kayaking to the landing zone (no hiking past the trailhead, Uluwehi Falls closed), access to Waimea Canyon from the canyon bottom only with state trails, campgrounds and shelters shut and many stream crossings destroyed, and Hunting Unit F below the Kōkeʻe Road junction. Kōkeʻe Road stayed closed. Check DLNR’s current list before any hike.
• Hurricane season to November 30, and flash floods at any time in the wet season. Never cross a flooded stream; water can rise from rain you cannot see falling upslope. Stay out of the ocean during brown-water advisories.
• Fresh water and leptospirosis. The Department of Health advises not swimming or wading in freshwater streams or ponds, especially with cuts or sores. Rat lungworm disease comes from slugs and snails: rinse all produce, and keep children from handling them.
• Surf and shorebreak. North and west shores turn dangerous without warning as the winter swells begin. Swim at lifeguarded beaches, and ask the lifeguard about currents and jellyfish.
• Altitude and cold. Maunakea and Haleakalā are at 9,000 to 14,000 feet: altitude sickness, freezing dawns, and steep unlit roads. Kīlauea’s vog and fountaining episodes can close parts of the park at short notice.
• Hunting and blaze orange. Seasons are set island by island and unit by unit, and pigs, goats and sheep are open year-round in many areas, including the Maunakea forest reserve. In October, dove seasons on private lands run from the first Saturday (October 3) through the last Sunday (October 25) on several islands. The fall game bird season opens the first Saturday in November (November 7, 2026) and runs to the last Sunday in January (January 31, 2027), mostly on weekends and state holidays. State rules require anyone hunting, guiding, assisting or accompanying a hunter in an area where firearms are allowed to wear an exterior shirt, vest, jacket or coat of commercially made solid blaze orange (or blaze-orange mesh no coarser than one-eighth inch), visible front and back; camouflage orange does not count. Hikers are not covered, but bright clothing in a public hunting area is sensible.