Mt Hood · Aug 28-30 · 15 days out Updated Thu Aug 13, 5:00 AM · refreshes daily at 5am

Everything is fine.

8 in 10chance the weekend is fine - clear or lightly hazy

A very large fire is burning about seventeen miles east of the house, and it will almost certainly still be burning during your trip. Right now the ocean air is winning — the monitor eight miles up the road reads 13, which is genuinely clean, and that onshore pattern is the normal late-August setup, so the most likely version of your weekend is a slightly hazy sky and nobody changing plans.

The thing that would wreck it is an east wind, which happens a few times each Oregon summer and would push that fire's smoke straight down US-26 into town; there is roughly a one-in-four chance at least one of your three days is genuinely bad.

Known now3 of 5 forecast sources already cover your dates
Next updateAug 15 — ECMWF ensemble
No horizonFire size and containment are observations, not forecasts — they can move this on any day
Decide byAug 24
What would change this
  • Evacuation zone at the housenone
  • US-26 open, Portland to Welchesopen
  • Air at Multorpor13 · Clear
  • Nearest fire outside 10 miles12.5 mi · Mitchell
  • Wind pushing smoke our wayno - at 0 mph

So what are the odds?

If we ran this weekend 100 times, here is how they would split. Hover a row to pick it out of the dots.

5 in 1051%Clear weekend AQI 0-50
Mt Hood sharp against blue sky, maybe a thin brown line low on the eastern horizon in the morning that burns off by ten. Kids outside all day, nobody mentions it.
nothing
3 in 1028%Hazy but fine AQI 50-100
Milky white sky, orange-ish sun, the far ridges look flat and washed out, and you can faintly smell campfire in the morning air. Sensitive people notice a scratchy throat; everyone else has a normal weekend.
Move the long hike to the morning, run the house fans on recirculate, and hand out masks to the two people with asthma.
1 in 1013%One smoky day AQI 100-150
You wake up Saturday and can't see the ridge across the valley; smoke has pooled in the Zigzag/Salmon river bottom overnight. Air smells strongly of smoke, eyes sting, it thins some by late afternoon.
That day becomes an indoor day: no hiking, no river, purifier running, windows shut. Trip still happens; one day gets sacrificed.
1 in 109%Real smoke episode AQI 150+
Persistent orange half-light, ash flecks on the car, headlights on at noon, sun a dull red disk. Smoke doesn't clear in the afternoon because the wind itself is delivering it. Possible Level 1 'Be Ready' notices in the corridor.
Cancel or cut short. This is a leave-early call, not a stay-inside call, and it's driven by an east wind that is also a fire-spread threat.
Clear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendClear weekendHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineHazy but fineOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayOne smoky dayReal smoke episodeReal smoke episodeReal smoke episodeReal smoke episodeReal smoke episodeReal smoke episodeReal smoke episodeReal smoke episode
Clear AQI 0-50
You can see the mountain. Nobody notices anything.
Hazy AQI 50-100
Visible haze, ridgelines soften, faint campfire smell.
Smoky AQI 100-150
Distinctly smoky, orange sun, eyes sting a little.
Bad AQI over 150
Mountain invisible. You smell it indoors.

Where the fires are

Fires near the house, drawn at their real shape from the federal perimeter data, over USGS terrain. Dashed rings are distance from the house; the shaded wedge is the only direction an east wind could carry smoke here from. Point at a fire for its details.

SandyBrightwoodWelchesGovernment Campan east wind would carry smoke from here10 mi20 miThe houseGrasshopper83,642 acres · 17.4 miAustin19.4 miMitchell12.5 miThe Narrows14.0 miRegan Hill17.8 miAustin Non-Stat20.4 mifire perimetersmall fire, size knownlocated, size not reported10 milesEverything within 60 milesGrasshopperBenchTen MileBeachcombHigh LavaAustinMitchellThe NarrowsRegan HillAustin Non-StatGorton Creek0579 Ten Mile0507
SandyBrightwoodWelchesGovernment Campan east wind would carry smoke from here20 mi40 miThe houseGrasshopper83,642 acres · 17.4 miBench67,071 acres · 45.5 miBeachcomb2,346 acres · 49.5 miAustin19.4 miMitchell12.5 miThe Narrows14.0 miRegan Hill17.8 miAustin Non-Stat20.4 mifire perimetersmall fire, size knownlocated, size not reported10 miles

Solid dots are fires too small to draw at this scale but whose size is known. A dashed circle would mean a fire that has been located but has no published perimeter - size unknown, not small.

Beyond this frame, and too far to threaten the house but close enough to add regional haze: Bench (67,071 acres, 45.5 mi SSE), Ten Mile (4,834 acres, 56.7 mi SE), Beachcomb (2,346 acres, 49.5 mi SSE), High Lava (1,211 acres, 38.9 mi NNW).

An outline is only as current as the last mapping flight, which is not the same as when this page refreshed. Last mapped — Grasshopper Aug 11 · Austin Aug 10 · Mitchell Aug 9 · The Narrows Aug 8. The oldest of these is The Narrows, 4 days behind.

Terrain: USGS 3DEP (public domain). Roads and water: © OpenStreetMap contributors (ODbL). Fire perimeters: NIFC.

Want to check it yourself, or see the rest of the state? The Oregonian's wildfire tracker is live and updates every 15 minutes.

Day by day

Fri Aug 28
Clear
likely 32 - could reach 108
11% chance of a smoky day
Sat Aug 29
Clear
likely 33 - could reach 108
11% chance of a smoky day
Sun Aug 30
Clear
likely 31 - could reach 105
10% chance of a smoky day

The specific odds

All three days clear50%
At least one smoky day (100+)22%
Two or more smoky days10%
At least one bad day (150+)10%
US-26 closed during the trip2%
Evacuation level at Welches6%

The one thing that would bring smoke here

6%of 156 ensemble member-days show the east wind that would bring smoke
vs 31% in a normal year — 25 points below normal
By trip day 08/28: 6% · 08/29: 12% · 08/30: 2%
By model gem global 21 members → 8% · gfs05 31 members → 5%
Base rate by year 2025: 22% · 2024: 44% · 2023: 44% · 2022: 22% · 2021: 22% (45 days, trip dates +/-3 days)

The long-range ensembles show less east-wind risk than a normal year — weak evidence, but pointing the right way.

Caveat: this counts days whose dominant wind is easterly, which at a valley site also picks up ordinary overnight down-valley drainage, not only the Gorge-outflow events that actually carry smoke. Forecast and base rate are measured the same way, so the gap is the meaningful part; the absolute percentages are not a chance-of-smoke.

When we'll actually know more

It is not one cut-off. Five sources arrive on five different dates, and the darker the strip, the more of them cover your weekend. Hover any day for the count.

Thu Aug 13Fri Aug 14Sat Aug 15Sun Aug 16Mon Aug 17Tue Aug 18Wed Aug 19Thu Aug 20Fri Aug 21Sat Aug 22Sun Aug 23Mon Aug 24Tue Aug 25Wed Aug 26Thu Aug 27Fri Aug 28Sat Aug 29Sun Aug 30Fire size & containmentECMWF ensembleAir-quality / smoke modelAug 13 - todayAug 30 - trip ends
Hover a dayto see the forecast we logged that morning and how much was known.

▲ Since 2026-08-10 the forecast has moved worse (+6 on the likely worst day) across 4 daily updates. Shading above shows source coverage, not this movement - hover a past day to see what we said that morning.

nowFire size & containment
how big the fires are and whether they are being held
nowLong-range ensembles (GEFS 0.5 + GEM)
wind direction, 52 members · reaches 32 days out
Aug 15ECMWF ensemble (51 members)
wind direction, the sharpest ensemble · reaches 13 days out
nowDeterministic weather (16-day)
day-by-day wind and temperature · reaches 15 days out
Aug 22Air-quality / smoke model (CAMS)
actual AQI at the house · reaches 6 days out

Why we think this

The whole forecast hinges on one fire and one wind direction. Grasshopper is 83,642 acres at 20% containment and 17.4 miles due east — and I checked the bearing rather than trusting the terrain note: due east at 45.32°N places it SOUTH of Mt Hood's summit, so the mountain is not between the house and the fire; the crest on that line is the low Barlow/Bennett Pass gap that channels directly down the Zigzag valley into Welches. Under the prevailing late-August marine regime the afternoon westerlies vent that valley eastward and the fire's smoke goes to central Oregon, which is precisely the evidence we have today: 84,000 acres burning 17 miles away and the Government Camp monitor reads 13. Against that, Welches sits in a river bottom that pools cold air, so on stable nights even a modest downslope drainage can settle smoke into town until midday — that mechanism alone produces the 50–100 days that are my central case, and NWS is already carrying 'Patchy Smoke' in the near-term forecast. The genuine tail is a thermal-trough east-wind event, the same pattern that drove Oregon's 2017 and 2020 disasters; such events occur a few times a season and last 1–3 days, giving maybe a 15–20% chance of overlapping this specific window, and if one lands, a fire directly upwind at 17 miles is a direct hit rather than a distant haze. I have also left room for a new ignition closer than the current ones — 15 days is plenty of lead time, and the small Regan Hill incident sits 17.8 miles WEST, on the upwind side, where acreage counts for far more.

A normal late August here is Clear - median AQI 12 across the last 4 years. On these exact dates: 2025: 16 · 2024: 10 · 2023: 11 · 2022: 11.

We are forecasting a worst day of 48, 36 points above that base rate. That departure rests entirely on the reasoning above; judge it for yourself.

What the bad version needs:
Grasshopper (83,642 acres, only 20% contained on Aug 13) keeps a smoldering, creeping interior through late August — an Oregon Cascade fire this size in mid-August essentially never goes out before the September rains, so there is a large smoke source 17 miles away on the trip dates regardless of what the containment number says. → A late-August thermal trough parks off the coast and the gradient flips offshore: dry east-to-northeast downslope wind over the crest. Critically, the mountain does NOT protect the house from this fire — Grasshopper is due EAST at 45.3°N, which puts it south of Mt Hood's summit, and the crest there (Barlow/Bennett Pass, roughly 4,100–4,600 ft) is a low gap that funnels straight into the Zigzag corridor and down US-26. → Smoke arrives on the wind by day and then pools overnight in the Welches river basin under a valley inversion; because the wind keeps resupplying it, the 24-hour average doesn't clear in the afternoon and settles somewhere between 100 and 250 for as long as the east wind holds — typically 1–3 days.
First visible signal: In the phone weather app: the wind direction at Government Camp and Portland flipping to E or NE, and a Red Flag Warning issued for east wind. Right behind it, the AirNow monitor at Government Camp (Multorpor, currently 13) climbing above 60 for a full day instead of just a hazy morning. - about 4 days ahead
Key drivers, and what would change our minds
  • Grasshopper: 83,642 acres, 20% contained, 17.4 miles east — will still be producing smoke on Aug 28–30 with ~90% confidence
  • The bearing check: the fire is south of Mt Hood's summit line, so the peak does not shield the house; Barlow Pass is a low funnel straight down US-26
  • Current observation is genuinely reassuring — nearest monitor at 13 with the fire already at full size, evidence the prevailing westerly regime protects this site
  • Welches is a valley cold-air pooling site: overnight drainage can concentrate smoke locally even without a synoptic wind shift
  • East-wind / thermal-trough risk in late August — low probability, high consequence, and the only path to 150+
  • Season running 1.57x normal (30-day mean daily max 15 vs 10 typical), a modest but real upward nudge
  • The Government Camp AQI reading on your phone sitting above 75 for a full day any time in the week before the trip — that means the smoke is already finding its way over
  • Seeing 'E' or 'NE' wind in the Welches hourly forecast for Aug 27–31, or a Red Flag Warning for east wind — that flips this from GO_WITH_CONTINGENCY toward RECONSIDER
  • Grasshopper containment jumping past 60% with no acreage growth by Aug 24 — that would push me toward a straight GO
  • A soaking Pacific front crossing Oregon in the week before the trip — a season-ending rain would make this a non-issue
  • Any new fire showing up within 25 miles on the west or southwest side of the house
  • A Level 1 evacuation notice appearing anywhere in the Zigzag–Rhododendron–Welches corridor

Fires within 60 miles

12.5 miMitchell S16 acres
14.0 miThe Narrows SSW5 acres
17.4 miGrasshopper E83,642 acres · 20% contained
17.8 miRegan Hill Wsize not yet reported
19.4 miAustin S719 acres · 0% contained
20.4 miAustin Non-Stat Ssize not yet reported
27.1 miGorton Creek NNEsize not yet reported

The biggest hole in this forecast: 3 of the nearby fires (Regan Hill, Austin Non-Stat, Gorton Creek) have no size reported yet. Whether those are 300-acre creepers or 20,000-acre runners is most of the answer.

Pack this regardless

  • A box of N95 or KN95 masks — enough for twelve people for three days, not four masks. Bandanas and surgical masks do nothing for PM2.5.
  • One or two portable HEPA air purifiers, or the parts for a box-fan-plus-MERV-13 filter (about $40 at any hardware store) to clean one room the group can retreat into.
  • Doubled asthma inhalers and rescue meds for anyone who uses them — the people who get hurt by smoke are the ones who ran out.
  • A genuine indoor plan: card and board games, a movie list, food that doesn't require the deck or the grill.
  • Full gas tank and a car with a working cabin filter set to recirculate, so leaving early is a decision and not a scramble.

If the weekend is clean you carried masks for nothing. If it is not, this is the difference between a bad weekend and a ruined one.

Watch list, and getting there

  • Government Camp / Multorpor PM2.5 monitor — the closest real sensor to both the house and the fire - Daily AQI above 75, or morning hourly readings above 100 on two consecutive days. That means the drainage/pooling mechanism has switched on. (fire.airnow.gov (map view) or the AirNow app)
  • Grasshopper Fire acreage and containment, especially any growth on the WEST flank - Containment still under 40% on Aug 24, or any reported westward growth toward Barlow Pass. (inciweb.nwcg.gov)
  • Wind direction in the Welches / Government Camp forecast - Any E or NE wind in the forecast for Aug 27–31, or a Red Flag Warning mentioning east wind. West or northwest wind is the good sign. (weather.gov (search Welches, OR) or any phone weather app's hourly wind)
  • Evacuation levels for the US-26 corridor - Any Level 1 'Be Ready' issued for Rhododendron, Zigzag, or Welches. (Clackamas County Sheriff / Oregon evacuation map (oregon.gov evacuation portal))
  • New fire starts WEST of the house — the upwind side under normal flow, where the small Regan Hill incident already sits 17.8 miles out - Any new incident within 25 miles on the west or southwest side reaching a few hundred acres. A fire upwind matters far more per acre than one downwind. (inciweb.nwcg.gov or the Watch Duty app)
Sandy19.4 mi
Brightwood15.5 mi
Welches14.3 mi

Distance from each point on the drive in to the nearest fire. TripCheck is the authority on closures.

How this is made, and what it cannot do

Fire perimeters from NIFC, evacuation zones from Oregon OEM, weather and alerts from NWS, air quality from AirNow (Multorpor, 8.7 mi away). The forecast is judged by Claude Opus 5 on the live data above, sampled 5 times and pooled conservatively.

It is a judgement, never scored against an outcome. Nobody forecasts smoke this far out: NOAA's smoke model runs 48 hours and the EPA's air-quality forecast is for tomorrow. Two-to-six weeks ahead is what meteorologists call the predictability desert. Anyone giving you a number for the trip right now - us included - is giving you a base rate with a story attached.

AQI here means the highest 24-hour PM2.5 value touching a day, at the house, on the local monitor scale - the same thing your phone shows. The model's own restatement of the target: “I am forecasting the US AQI for PM2.5 as a 24-hour-average quantity at the house in Welches, Oregon — for each calendar day, the highest 24-hour AQI value touching that day, on the local monitor scale a phone app would display (already calibrated from the model scale; I applied no further correction). 'Worst day of trip' is the single largest of those three daily values across Aug 28, 29, and 30, not their average.”

Updated daily at 5am. A convenience, not an authority -
if officials issue an evacuation order, follow it.