How Cold Is an Alaska Cruise?

Alaska in summer is milder than most people expect and colder than most people prepare for, and both of those statements are true at once. Daytime highs in the ports run 55 to 68 degrees Fahrenheit, but an open deck at a glacier face in wind can feel closer to 35.

Two things are true about Alaska temperatures and they seem to contradict each other. It is milder than people expect: a July day in Juneau averages around 64 degrees Fahrenheit, which is an unremarkable summer day in most of northern Europe. And it is colder than people prepare for, because the number that matters is not the air temperature in town but what it feels like on an open deck in wind, a quarter of a mile from several thousand feet of ice.

Typical temperatures by month

Those are the numbers people plan around, and they are the wrong numbers.

The temperatures that actually matter

At a glacier face

Glaciers generate their own weather. Cold, dense air flows downhill off an icefield in what is called a katabatic wind, and it arrives at the water where your ship is holding position. On a Glacier Bay or Hubbard morning it is common for the temperature at the ice to be 10 to 15 degrees Fahrenheit below the reading at the mouth of the bay, with wind on top of that.

A 62 degree June day in Juneau can be a 45 degree experience with wind at Margerie Glacier, and you will be standing still in it for an hour.

On a moving deck

The ship makes its own wind. At 18 knots, even a still day produces a 20 mile per hour apparent wind on an exposed deck, and the wind chill from that is substantial. This is why the forward observation lounges on ships like Norwegian Bliss and Royal Caribbean Quantum class matter so much in Alaska.

On a small boat

Whale watching boats feel considerably colder than the same temperature ashore. You are wet from spray, you are stationary for long periods while the boat drifts, and there is nothing between you and the wind. Operators supply blankets for a reason.

In the rain

Wet clothing conducts heat away from your body far faster than dry clothing. A 58 degree day in Ketchikan with persistent rain and an inadequate jacket is genuinely unpleasant in a way that 58 degrees and dry is not. This is the single strongest argument for a properly waterproof shell rather than a water resistant one.

What this means for what you pack

The answer is layers, and specifically two thin mid layers rather than one thick one, because that gives you four useful configurations instead of two.

• Base plus shell for a mild wet port day
• Base plus fleece plus shell for most of the trip
• Base plus fleece plus down plus shell for a glacier morning on an open deck
• Base plus fleece for a warm afternoon in Skagway

Add a hat that covers the ears and light gloves. They weigh almost nothing and they are the difference between staying outside for the full hour at the glacier and retreating after fifteen minutes. The full list is in our packing guide.

The one thing nobody warns you about

In late June, Juneau gets about eighteen hours of daylight and never becomes properly dark. That has nothing to do with temperature and everything to do with how the trip feels. People stay up later than they intend, wake earlier than they meant to, and are colder than they should be on a 6:00 am deck because they went outside in what they were sleeping in.

Bring a sleep mask, and put your fleece by the door.

Does the month change the answer?

Less than you would think. The difference between a May glacier morning and a July glacier morning is real but modest, perhaps seven or eight degrees. The difference between a sheltered deck and an exposed one on the same morning is larger. The difference between a proper waterproof shell and a fashion raincoat is larger still.

Choose your month for daylight, wildlife and price, and solve the temperature problem with clothing rather than with the calendar.