High Season in Alaska: June through August
Quirks & Perks of Sailing in Season: Temperatures are at their warmest (highs: 50s to 70s Fahrenheit), plus the further into the summer you are, the better your chances of seeing wildlife on the various expeditions. The downside: Demand is so strong, you need to book months (better yet, a year) in advance to get the best land and tour packages. Keep in mind, with so many ships sailing Alaska now, there can be a tremendous amount of congestion in small-town ports.
To minimize joining the masses, select a ship that sails during the week. For a pricing advantage, northbound glacier routes tend to be cheaper than southbound.
Low Season: May and September
Quirks & Perks of Sailing in the Off Season: Shoulder-season perks include smaller crowds and cheaper prices as a result of the weather gamble (highs: 50s to 60s) and the possibility of snow. May sailings typically encounter less rain than summer cruises, and the scenery is arguably more beautiful with more snow-capped mountains; September cruisers benefit from end-of-season souvenir bargains and a possibility of catching the northern lights. A few caveats: Shore excursions have a greater chance of being canceled than in high season, especially boat and helicopter tours. In addition, Denali National Park has been known to close in September due to snow.