Summer (late May through early September) is peak season: the Mendenhall Glacier Visitor Center is fully open, humpback whales feed in peak numbers, Pack Creek bear permits are active (July 5–August 25), and Juneau's 18+ hours of daylight let you hike and kayak well into the evening. July offers the warmest days (avg high 64°F) and the highest probability of clearer skies, though rain is always possible — Juneau averages 230 rainy days a year. May and early September offer a rewarding balance of mild weather, thinner cruise-ship crowds, and lower prices. Fall (September–October) brings aurora borealis viewing as darkness returns, vivid fall colors, and salmon spawning at Steep Creek. Winter is quiet, dark, and snowy; Eaglecrest Ski Area and northern lights are the main draws.
| Month | High (°F) | Low (°F) | Notes |
|---|---|---|---|
| Jan | 30 | 24 | Cold and wet; roughly 12 inches of rain/snow; ~6 hours of daylight. |
| Feb | 31 | 24 | Still cold; precipitation eases slightly; days slowly lengthening. |
| Mar | 35 | 27 | Crisp and wet; daylight expanding; Mendenhall wetlands come alive. |
| Apr | 43 | 34 | Crisp and wet; Alaska Folk Festival and Jazz & Classics Festival. |
| May | 54 | 41 | Cool and wet; cruise season begins; whale watching and kayaking open. |
| Jun | 61 | 50 | Mild with 18+ hours of daylight near the solstice; Celebration (biennial) in early June. |
| Jul | 64 | 54 | Warmest month; peak whale watching and bear viewing; long bright evenings. |
| Aug | 64 | 53 | Warm and wet; salmon spawn at Steep Creek; peak bear activity at Pack Creek. |
| Sep | 57 | 48 | Cool and very wet; aurora returns; thinning cruise crowds; beautiful fall color. |
| Oct | 46 | 38 | Cool and wet; aurora season underway; Eaglecrest ski area preps to open. |
| Nov | 34 | 28 | Crisp and wet; locals' season; northern lights viewing on clear nights. |
| Dec | 30 | 23 | Cold and dark; ~6 hours of daylight; Eaglecrest skiing and aurora viewing. |