Washington · Rock climbing · Index

(A) Great Northern Slab

Great Northern Slab in Washington has 12 routes across 9 grades, offering mixed and sport climbing.

12 routes
5.6 – 5.11b/c
Trad · Sport · Mixed

Is (A) Great Northern Slab open right now?

Closure in the area

There's a closure order in Mt. Baker-Snoqualmie National Forest. It doesn't name (A) Great Northern Slab, so check the source for the area it covers (2 listed).

As of · Source: USFS · Mt. Baker-Snoqualmie National Forest. Agencies don't list every closure — check before you go.

Best time to visit (A) Great Northern Slab

Best months: July–September. Best months have typical highs of 55–85 °F, lows of 30 °F or warmer (32 °F where the station doesn't record snow), at most one snowy day and no more than 12 wet days.

  1. Jan

    42° / 31°

    20 wet · 4 snow

  2. Feb

    47° / 32°

    17 wet · 2 snow

  3. Mar

    52° / 34°

    19 wet · 2 snow

  4. Apr

    59° / 38°

    18 wet

  5. May

    66° / 44°

    16 wet

  6. Jun

    69° / 48°

    13 wet

  7. Jul

    77° / 52°

    7 wet

  8. Aug

    77° / 52°

    7 wet

  9. Sep

    71° / 48°

    11 wet

  10. Oct

    58° / 41°

    16 wet

  11. Nov

    47° / 36°

    20 wet · 2 snow

  12. Dec

    41° / 32°

    20 wet · 5 snow

Typical high / low (°F) and days with rain or snow, 1991–2020. Measured at Baring, WA, 5.3 mi away at 770 ft. Source: NOAA NCEI U.S. Climate Normals 1991–2020.

Closures we've recorded since August 2026

  • Campfire Ban in Effect Forest-wide

    Mt. Baker-Snoqualmie National Forest · Order dated July 21, 2026; seen Aug 23, 2026 → lifted Sep 15, 2026 · Forest Service

Great Northern Slab is a climbing area in the Skykomish Ranger District of Mt. Baker-Snoqualmie National Forest in Washington, about 0.1 mile from the Index Town Wall Trail and the Lower Wall & Lower Lump Boulders. It sits among several other climbing spots, including (B) Sonic Slab, and is close to the Crescent Trail for a walk. The climbing here is mostly traditional, with 9 trad routes and 2 sport routes among the 12 listed. The YDS grades run from 5.6 up to 5.11b/c. Aries (aka The Lizard) is a trad route at 5.8+, and Sandy Corner is a trad route at 5.10d. Air Over Aries is a sport route at 5.11a. Summer is the most comfortable time to climb. Typical averages from the nearby Baring weather station show July and August highs around 77°F with only about 7 wet days a month, while winter brings highs in the low 40s and frequent snow days. Heybrook Lookout is about 1.9 miles away for camping, and Anderson Creek offers canoeing about 1.8 miles off.

Routes (12)

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