What to Pack for a Cruise to Alaska in September, the Wettest Month of the Season

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Here’s a number the glossy brochures leave out. In Ketchikan, the normal September rainfall is 14.30 inches. In July it’s 7.33.

Both figures come from NOAA’s official 1991–2020 climate normals, and Ketchikan isn’t unusual. At every major Alaska cruise stop we checked, September is the wettest month of the whole May-to-September season. It also brings cheaper fares, the first dark skies for the northern lights, and the yellow leaves.

So you’re not packing for “Alaska.” You’re packing for a wet, cool, sometimes gorgeous autumn week, and that needs a different suitcase from a July trip.

What to Pack for a Cruise to Alaska in September

Pack for rain first and cold second. You need a waterproof hooded jacket, waterproof pants, a warm fleece or insulated mid-layer, a beanie and gloves, and shoes that stay dry. Average September highs at the ports run in the mid-50s °F, with lows in the 40s. Bring binoculars and a camera with a night mode, because late September is the start of aurora season. You don’t need a parka or snow boots.

How September Compares With July, Port by Port

We pulled the official monthly normals for six cruise stops from NOAA’s National Centers for Environmental Information. These are 30-year averages (1991–2020) from each town’s weather station. The Juneau and Ketchikan figures match the NOAA climate tables on Wikipedia’s Juneau and Ketchikan pages.

Port	September high / low	September rain	July rain	Wet days in September
Ketchikan	58.9°F / 48.3°F	14.30 in	7.33 in	19.5
Sitka	57.9°F / 48.5°F	11.69 in	4.62 in	22.4
Juneau	56.1°F / 44.1°F	9.15 in	5.14 in	22.3
Glacier Bay (park station)	53.5°F / 43.3°F	9.16 in	4.76 in	not published
Skagway	57.0°F / 46.1°F	3.89 in	1.38 in	17.4
Seward	55.7°F / 43.4°F	9.90 in	3.11 in	17.1

Three things stand out:

• It roughly doubles. Juneau goes from 5.14 inches in July to 9.15 in September, its wettest month of the entire year. Sitka gets two and a half times as much, and Seward more than three times.
• Rain is the default, not the exception. Sitka and Juneau average about 22 wet days in a 30-day month.
• Skagway is the dry one. It averages under 4 inches in September, so if you have a big outdoor excursion booked there, your odds of a dry day are better.

Cruise lines quote wider ranges. Princess says September temperatures “typically range from about 45 – 70°F.” That isn’t wrong: averages hide warm afternoons and chilly mornings. But NOAA’s normals show that a typical September afternoon at these ports is in the mid-50s, not the high 60s, so pack for the average and treat a warm day as a bonus.

Build Your Suitcase in Layers

The cruise lines and the National Park Service agree on one rule: several thin layers beat one bulky coat. Holland America’s packing list puts it plainly: “a lightweight, waterproof outer shell over warm base layers beats bulky winter gear.” Here’s how that works in September:

• Outer shell: a properly waterproof jacket with a hood. Not water-resistant, waterproof. Make sure it fits over a fleece. Princess says “Waterproof jackets, pants, and bags will be your best friends.”
• Rain pants. This is the item July cruisers skip and September cruisers regret skipping. Holland America suggests “lightweight waterproof pants that slip over your base layers or jeans.” Wet jeans on a two-hour excursion are miserable.
• Warm mid-layer. A fleece, a light down jacket or a thick sweater. Holland America notes “a heavier jacket becomes most useful by September,” and Princess says the later season needs “warm, insulated clothing.”
• Base layers. Princess recommends “moisture-wicking base layers.” Thermal tops double as pyjamas on a cold balcony.
• Hat and gloves. A beanie and light gloves (Princess), plus, in Holland America’s words, a “rainproof hat that will stay put in gusts of wind.”
• Waterproof shoes or boots. Both lines call them essential. Break them in before the trip, and pack extra socks: wet feet are the fastest way to end a port day early.
• A dry bag or waterproof daypack for your phone, cruise card and ID on the way ashore.

For dinners aboard, pack as you would for any cruise. Princess’s page notes that formal nights call for “cocktail dresses or gowns for women and tuxedos or suits for men.” Our formal night guide has every major line’s rule.

Glacier Day Is the Coldest Day of Your Cruise

Glacier Bay’s own station is the chilliest in our table, with an average September high of 53.5°F. And you won’t spend the day in town. You’ll be standing on an open deck, near ice, while the ship moves. The National Park Service tells cruise passengers to “bring plenty of warm layers” and rain gear, and warns that “the moisture and cool temperatures may make it seem colder than you expect.”

The park also says the best place to be is “outside, especially during the time near the glaciers,” and that rangers often board “in the early morning.” So on glacier day, wear everything: base layer, fleece, shell, hat and gloves. Keep binoculars around your neck. The NPS has a whole section titled “Bring Binoculars!”, and Princess calls them “invaluable for wildlife viewing.”

What Changes as the Month Goes On

The days get shorter, fast. According to the U.S. Naval Observatory, Juneau’s sun rises at 5:58 a.m. and sets at 7:56 p.m. on September 1, about 14 hours of daylight. By September 30 it’s 7:01 a.m. to 6:33 p.m., about 11 and a half hours. Sunrise-Sunset.org gives the same times to within a minute. On the June solstice, Juneau gets more than 18 hours. Late-month evenings on deck are dark and cold, so plan your warm layers for after dinner, not just for port days.

The northern lights become possible. Travel Alaska, the state’s official tourism site, says “by late August there’s enough darkness to view the aurora borealis,” though the best viewing is in the Interior and Arctic, not the coast. Celebrity puts the aurora season at “late August to mid-April” and says it needs “crisp, clear skies.” With 17 to 22 wet days in a typical September, clear nights aren’t guaranteed. Treat an aurora as luck, not a plan. Celebrity suggests top decks, forward observation areas or a balcony with the cabin lights off, and a phone with night mode or long exposure.

Autumn shows up. Travel Alaska describes “yellow and orange leaves” against “snow-dusted mountains” and bears “fattening up” before hibernation. Princess says wildlife is “highly active thanks to salmon runs,” with whale and bear viewing.

What You Can Leave at Home

• A heavy winter parka. Average lows at the ports stay in the 40s °F. A shell over a fleece does the same job and dries faster.
• Snow boots. Waterproof walking shoes or light hiking boots are enough for port days. If you book a specialist excursion, check its kit list.
• A big umbrella. It’s fine on Creek Street. On a windy deck, a hood works better.
• Too many summer clothes. One pair of shorts covers the gym, the hot tub and the rare warm afternoon.

Before You Close the Suitcase

Check the forecast for each port a few days out. Normals are averages, and a single week can run well wetter or drier. If your itinerary includes a train, a hike or a small-boat excursion, pack the rain pants in your daypack, not your cabin. And if a September fare looks cheap, that’s expected: Travel Alaska notes that Inside Passage cruises in September and October are “typically cheaper than peak season cruises.” Put some of the savings into a good rain jacket.

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Cruise Chaos earns nothing from cruise lines, travel agents, outdoor brands or booking links. Every fact here links to where we read it, and we downloaded the NOAA climate normals and the Naval Observatory sun times ourselves on October 29, 2026. If something has changed, tell us and we’ll correct it.

Coming up on Cruise Chaos: is it safe to cruise to the Bahamas in October, at the tail end of hurricane season?

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Sources

• NOAA NCEI: U.S. Climate Normals, 1991–2020 (monthly normals for Ketchikan, Sitka, Juneau, Skagway, Seward and Glacier Bay stations, retrieved October 29, 2026)
• Wikipedia: Juneau, Alaska (climate table, NOAA 1991–2020)
• Wikipedia: Ketchikan, Alaska (climate table, NOAA 1991–2020)
• U.S. Naval Observatory: Sun and Moon Data for One Day (Juneau, June 21, September 1 and September 30, 2026)
• Sunrise-Sunset.org: Juneau, Alaska
• National Park Service: Glacier Bay, Cruise Ship Visitors
• Travel Alaska: Top Reasons to Visit Alaska in the Fall
• Holland America Line: Alaska Cruise Packing List
• Princess Cruises: Comprehensive Alaska Cruise Packing List
• Princess Cruises: Alaska Cruise in September (updated April 13, 2026)
• Celebrity Cruises: Northern Lights From a Cruise Ship in Alaska (updated July 22, 2026)