The intel you earn, not the intel you're given.
This is the chapter families ask for. Here are the JBLM-specific realities families learn three months in that the official PCS materials never mention.
The Pacific Northwest gray season is a real adjustment. Three months of the year, the region will sell you on itself — long mountain summers, blue water, hiking trails twenty minutes from the gate. The other nine months are gray. Families coming from sunnier postings should plan for that, not romanticize it. It's not a deal-breaker for most, but it's the single most underestimated thing about life at JBLM.
Washington has no state income tax — but a high sales tax. Tax math at JBLM looks different than at most Army installations. There's no state income tax to plan around (favorable for retiring or transitioning service members), but Washington's sales tax is among the highest in the country, and it stacks with local rates. A dollar from BAH goes about as far at the grocery store as it does at most posts; a dollar from take-home pay goes meaningfully further on paper because of the no-income-tax structure.
Most online "JBLM info" is actually Army info. The joint-base structure means that a lot of relocation guides, MWR pages, and unofficial PCS forums treat the McChord side as an afterthought. If you're an Air Force family and the materials you're reading don't name the 627th Air Base Group, the 62nd Airlift Wing, or McChord Main Gate, you're reading Army-side material. The McChord-side procedural reality is on the Life On Post page.
The Nisqually River valley sits inside official Mt. Rainier volcanic hazard zones. Mt. Rainier is a designated active volcano (one of the USGS Decade Volcanoes — the 16 most-monitored volcanoes in the world). Pierce County maps lahar hazard zones along five river drainages from the mountain: Puyallup, Carbon, White, Nisqually, and Cowlitz. Of those, the Nisqually valley is the one near JBLM — and it has a regulated land-use category under Pierce County Code (Volcanic Hazard Areas, 18E.60.020). Most off-post housing JBLM families typically consider — Lakewood proper, DuPont's bluff neighborhoods, Steilacoom uplands, most of Lacey — sits on higher ground outside the inundation zones. But properties along the Nisqually river bottoms specifically can be inside the hazard zone, and that affects insurance and resale conversations. If you're considering a property near the Nisqually, ask explicitly whether it falls inside a designated volcanic hazard area. Don't assume the agent or builder will volunteer it.
Madigan's referral patterns are their own thing. Madigan Army Medical Center is a major treatment facility serving both Army and Air Force families across JBLM. It runs differently than a typical Army community hospital, and TRICARE referral routing for specialty care can mean longer wait times than families expect. The 62nd Medical Squadron operates the McChord Clinic on the Air Force side; higher-acuity care still routes through Madigan. Plan accordingly if anyone in your family has ongoing specialty care needs.