Mt Hood · Aug 28-30 · 15 days out Updated Thu Aug 13, 12:37 PM · refreshes daily at 5am

Everything is fine.

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

Right now the air at the house is clean, and the pattern keeping it clean — cool ocean air pushing inland every morning, with fog in the valley — is the normal late-August setup for the west side of Mt Hood. The big fire seventeen miles east will still be burning on your dates, so the entire question is wind direction, and the most likely outcome is a worst day somewhere in the teens to thirties, which is ordinary summer air.

There is roughly a one-in-six chance an east wind pulls that fire's smoke down the Zigzag valley for a day or two and makes one day genuinely unpleasant — worth packing for, not worth cancelling over.

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 21
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 - NW at 2 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.

6 in 1057%Clear weekend AQI 0-50
Morning fog burning off to blue sky; maybe a milky band low on the eastern horizon near the mountain, but the air smells like fir, not campfire, and nobody comments on it.
nothing
3 in 1025%Hazy but fine AQI 50-100
Flat white sky, the ridgelines across the valley look washed out, a faint smoke smell at breakfast that fades by afternoon. Healthy people are fine; one or two people with asthma notice it.
Do the hike in the morning before the valley heats up; keep windows shut overnight and run a filter in whichever room the sensitive folks sleep in.
1 in 1011%One smoky day AQI 100-150
The sun is an orange disc you can look at, you can taste the smoke, the far side of the valley disappears. Ash flecks possible on car hoods. One day of this, then it clears or drops back to haze.
Cancel outdoor plans for that day, keep everyone inside with the box-fan filter running, N95s for anyone who goes out, and consider a day trip west toward Portland or the coast where the air is usually clean.
1 in 107%Real smoke episode AQI 150+
Visibility under a mile, headlights on at midday, indoor air noticeably smoky even with windows shut, everyone's eyes and throat hurt. Persists two to three days rather than one.
Leave, or never come. If you're already there, drive west on US-26 — you're usually out of it by Sandy or Gresham. Anyone with asthma, heart disease, a pregnancy, or a small child should not stay.
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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 houseGrasshopper85,114 acres · 17.4 miAustin1,430 acres · 19.4 miMitchell12.5 miThe Narrows14.0 miRegan Hill17.8 miAustin Non-Stat20.4 mifire perimetersmall fire, size knownlocated, size not reported10 milesEverything within 60 milesGrasshopperBenchTen MileBeachcombAustinHigh LavaMitchellThe NarrowsRegan HillAustin Non-StatGorton Creek0579 Ten Mile0507
SandyBrightwoodWelchesGovernment Campan east wind would carry smoke from here20 mi40 miThe houseGrasshopper85,114 acres · 17.4 miBench67,071 acres · 45.5 miBeachcomb2,346 acres · 49.5 miAustin1,430 acres · 19.4 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. Outlines flown — Grasshopper Aug 11 · Austin Aug 10 · Mitchell Aug 9 · The Narrows Aug 8. The oldest is The Narrows, 5 days behind. Acreage and containment are refreshed far more often than the outlines are re-flown — those figures were last updated Aug 13, 11:54 AM, so a fire may already be larger than the shape drawn for it.

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 22 - could reach 85
8% chance of a smoky day
Sat Aug 29
Clear
likely 24 - could reach 85
9% chance of a smoky day
Sun Aug 30
Clear
likely 25 - could reach 88
10% chance of a smoky day

The specific odds

All three days clear56%
At least one smoky day (100+)18%
Two or more smoky days9%
At least one bad day (150+)7%
US-26 closed during the trip3%
Evacuation level at Welches7%

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: 10% · 08/29: 8% · 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 better (-11 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 dominant fact is that a large, poorly contained fire (Grasshopper, 85k acres at 20%) sits 17 miles east and will still be producing smoke on Aug 28-30 — fires that size in a record-drought Oregon year routinely burn into late September, and the first season-ending west-slope rain is climatologically mid-September at the earliest. Despite that, the monitor 8.7 miles away reads 13 right now, which tells you the transport, not the fuel, is the binding constraint: the summer marine pattern vents the Sandy valley westward and pushes fire smoke away from the house, and that pattern held all week with fog and light NW winds. The failure mode is an offshore pressure gradient — and I want to be explicit that Mt Hood does NOT protect you from it, because east wind channels down through the Cascade gaps into the Zigzag/Sandy corridor and Welches sits at the outlet, which is exactly why the 2020 and 2017 west-side events hit valleys like this one so hard. Two fires are on the house's own side of the crest with no terrain in between — Austin at 19 miles S (1,430 acres, 0% contained) and Regan Hill at 18 miles W, whose size the pack doesn't report — and the westerly one is upwind in the ordinary onshore flow, which is part of why I'm fattening the 50-100 band above what pure climatology would give.

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 31, 19 points above that base rate. That departure rests entirely on the reasoning above; judge it for yourself.

What the bad version needs:
Grasshopper (85,114 acres, only 20% contained) keeps burning through late August — an Oregon fire that size in a record-drought year does not go out before the first real rain, which historically arrives mid-September or later. → A surface high builds east of the Cascades and sets up an offshore pressure gradient, flipping the wind from the usual northwest to east. The crest does not shield the house from this — east wind funnels through the Cascade gaps and accelerates DOWN the Zigzag/Sandy corridor, and Welches sits at the bottom of it, directly downwind of the fire at 17 miles. → Smoke arrives in the valley during the day, then the overnight inversion and morning fog trap it near the ground instead of venting it, so the 24-hour average — not just the afternoon peak — lands in the 150-250 range for one to two days.
First visible signal: The plain-language NWS forecast for Welches or Government Camp starts listing wind from the EAST or NORTHEAST instead of NW/W for two periods in a row — and PM2.5 starts climbing at the Government Camp and Hood River monitors on the AirNow map before it climbs at Welches. - about 3 days ahead
Key drivers, and what would change our minds
  • Grasshopper (85,114 ac, 20% contained, 17 mi E) will still be burning on the trip dates — near certainty
  • Marine/onshore flow is the default late-August pattern and is currently holding the house at AQI 13 despite that fire
  • Terrain does NOT shield: an east-wind gradient channels smoke down the Zigzag/Sandy corridor straight to Welches
  • Austin (19 mi S, 0% contained) and Regan Hill (18 mi W, size unknown) are on the house's side of the crest with no barrier
  • Season anomaly of 1.57x measured locally — already prices in this year's severity as it has actually shown up at this address
  • The 4-year archive excludes 2017/2018/2020/2021, so the upper tail is under-sampled rather than measured at zero
  • The Welches forecast on weather.gov showing east or northeast wind for the trip window — that flips this from GO to DECIDE_LATER immediately
  • Government Camp's AQI running above 75 for two days in a row the week before — it's the upstream canary for you
  • A new fire appearing on Watch Duty anywhere in the Clackamas or Salmon River drainages, i.e. west or south of the house
  • Grasshopper containment going backwards or acreage jumping past ~120,000
  • Any Level 1 evacuation notice posted for Zigzag, Rhododendron, or Welches
  • Conversely: a Pacific front with measurable rain forecast for the west Cascades in the week before the trip would push me to a straight GO — that ends the smoke question for days

Fires within 60 miles

12.5 miMitchell S16 acres
14.0 miThe Narrows SSW2 acres
17.4 miGrasshopper E85,114 acres · 20% contained
17.8 miRegan Hill Wsize not yet reported
19.4 miAustin S1,430 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 dozen N95 or KN95 masks (not cloth, not surgical — they do nothing for smoke)
  • Two 20-inch box fans and four MERV-13 furnace filters — tape a filter to the back of each fan and you have a cheap, genuinely effective room filter for about $60
  • One real HEPA purifier for the main living room if anyone owns one
  • Every inhaler, allergy med, and eye drop anyone in the group uses — plus a spare
  • A rainy-day plan that works indoors for twelve people: cards, board games, a projector
  • Enough flexibility to swap a hike for a drive west — Portland, the Gorge's west end, or the coast are usually clean when Welches isn't

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

  • 24-hour PM2.5 at Government Camp / Multorpor and Hood River — these go up before Welches does under east wind - Government Camp over 75 on any day in the three days before the trip (fire.airnow.gov)
  • Wind direction in the plain forecast for Welches - Wind listed from the E, NE, or SE for two consecutive periods anywhere in the trip window (forecast.weather.gov (search Welches, OR))
  • Grasshopper containment and acreage - Containment stalls below 40% by Aug 24, or acreage jumps more than 10,000 in a single day (inciweb.wildfire.gov)
  • Regan Hill fire size — it's 18 miles due WEST, which is upwind under the ordinary onshore pattern, and the evidence pack has no acreage for it. This is the one unknown that could make an otherwise normal weekend hazy. - Regan Hill reported over ~500 acres or with any growth notes (watchduty.org)
  • Any NEW fire start within 25 miles, especially west or south of Welches (same side of the crest, no terrain between it and you) - Any new named start in the Clackamas, Salmon-Huckleberry, or Sandy River drainages (watchduty.org)
  • Evacuation levels for Clackamas County - Any Level 1 in the Zigzag, Rhododendron, or Welches area (Clackamas County Sheriff / oregon.gov evacuation map)
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.

How thin the history is. The air-quality record for this spot begins in 2022, so "normal" here is built from just 4 years (2022, 2023, 2024, 2025). In those 28 sampled days the worst single day was AQI 22, and none reached 100.

That record has never seen a bad Oregon smoke year — not 2020, when Portland sat above AQI 500 for days, nor 2017, 2018 or 2021. So the base rate below is drawn entirely from calm years, and the upper end of our range is an estimate rather than something history has shown us. It is the main reason not to read the good news too confidently.

Are these forecasts any good? Accuracy checking started Aug 13. 0 forecast-days scored so far — far too few to claim anything. This is the only part of the page that can ever be proved wrong.

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 EPA AQI for PM2.5 computed as a 24-hour average concentration — the single highest such 24-hour value touching any of Aug 28, 29, or 30 at the Welches house, reported on the local monitor scale that a phone app like AirNow would display, not the raw model scale. 'Worst day of trip' is the maximum of those three daily values, not their average, and I have applied no bias correction of my own on top of the calibration already in the evidence.”

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