Drainage is the one home maintenance category with a genuine scheduling conflict. The evidence appears in February and the work happens in July, which means most people forget between the two.
Document in winter
During heavy rain, go outside and record what actually happens. Photographs and a note of the date are enough.
Where does water pool? Which downspouts discharge badly? Is anything overflowing? Which direction does surface water run near the house? Where does the crawl space vent sit relative to standing water?
That record is what makes summer work targeted. Without it you are describing a problem from memory to a contractor standing on dry ground, and the resulting work is a guess.
Why summer is right for the work
Excavation in saturated ground is difficult, messy and produces poor results. Compaction is unreliable, trenches collapse, and restoring the surface afterwards is far harder.
Dry ground allows proper trenching, correct bedding of drainage lines, reliable compaction and good surface restoration. Any planting or seeding to restore the area also establishes better.
The order of operations
Start with the cheapest thing that might work.
Downspout extensions. Frequently the entire problem. Getting water clear of the foundation solves a surprising proportion of crawl space complaints, and it costs almost nothing.
Grading. Ensuring ground slopes away from the house. Soil settles over decades and landscaping gets added without regard to it, so older properties frequently drain toward the building.
Surface drainage. Channels or catch basins where water collects in defined places.
French drains and subsurface systems. Where the above is insufficient. More expensive and more disruptive, and worth doing properly rather than partially.
Contractors who lead with the most expensive option before establishing whether the cheap ones would work are worth questioning.
Sequence with landscaping
Drainage work disturbs ground. Doing it after new planting, turf or hardscaping means paying for both twice.
If you are planning both, drainage comes first. This is one of the more common and avoidable sequencing mistakes.
The Thurston County reality
Olympia and the southern Sound get more annual rainfall than Seattle, on flatter ground with slower-draining soils. Drainage work is routine there rather than exceptional, and systems sized for average conditions can be marginal.
Where drainage cannot fully solve it
In the Skagit valley floor and parts of Thurston County, high water tables mean groundwater arrives from beneath regardless of how well surface water is handled.
Drainage helps, but there is a real ceiling. A contractor promising that surface drainage will completely resolve a crawl space problem in those areas may be overpromising, and encapsulation with active humidity control is often the honest answer.
Check it worked
The following winter, go out in the rain again and compare against your photographs. Drainage work is one of the few improvements you can genuinely verify, and doing so tells you whether to stop or continue.