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

Still on, but worth watching.

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

Fires are burning on three sides of this house right now, and the monitor nine miles up the road is already reading smoky enough that the weather service has an air-quality alert out. Two weeks is long enough for the wind pattern to flip several times, so the most likely weekend is a hazy one — washed-out mountain views, orange sunsets, some people's eyes stinging — with our best guess for the worst single day landing around 90, the top of the yellow zone bleeding into orange.

The real risk isn't that average, it's a two- or three-day east-wind episode funneling smoke over Government Camp and down the Zigzag valley into Welches; that's roughly a one-in-five chance, and it's a reason to pack filtration and keep a bail-out plan, not a reason to cancel today.

Known now4 of 5 forecast sources already cover your dates

Next updateAug 22 — Air-quality / smoke model

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 Multorpor95 · Hazy
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.

2 in 1017%	Clear weekend AQI 0-50 Sharp views of Mt Hood from the Welches meadow, blue sky, no smell of smoke; kids in the river all afternoon and nobody thinks about air once.	nothing
4 in 1042%	Hazy but fine AQI 50-100 Milky white sky, the mountain looks flat and distant, a faint campfire smell in the morning that burns off by noon; sunsets are lurid orange. A couple of people with allergies feel scratchy.	Do the hard hike in the morning before the valley warms, run one purifier in whichever bedroom the asthmatic sleeps in, keep windows shut overnight and open midday.
2 in 1024%	One smoky day AQI 100-150 You can see the smoke as a gray layer, not just haze; the far side of the valley goes soft. Sun is a dull disc. Sensitive people cough, everyone's eyes water on a walk.	That day becomes an indoor day — purifiers running in the main room and bedrooms, N95s for anyone who goes out, cancel the ridge hike, drive to the coast for the afternoon if people are restless.
2 in 1016%	Real smoke episode AQI 150+ Ash-lit brown light all day, you smell it indoors, the far treeline disappears. Headaches by afternoon, healthy adults notice their chest. It does not clear overnight — you wake up to the same thing.	Cut the trip short or relocate the whole group to the coast; a house full of twelve people with no filtration in 150+ smoke is a miserable and genuinely unhealthy weekend, especially for any kids, pregnant people, or anyone over 65.

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.

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 12 · Mitchell Aug 9. The oldest is Mitchell, 5 days behind. Acreage and containment are refreshed far more often than the outlines are re-flown — those figures were last updated Aug 14, 6:44 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

Hazy

likely 62 - could reach 142

22% chance of a smoky day

Sat Aug 29

Hazy

likely 65 - could reach 148

24% chance of a smoky day

Sun Aug 30

Hazy

likely 66 - could reach 148

24% chance of a smoky day

The specific odds

All three days clear18%

At least one smoky day (100+)42%

Two or more smoky days24%

At least one bad day (150+)15%

US-26 closed during the trip3%

Evacuation level at Welches10%

The one thing that would bring smoke here

18%of 156 ensemble member-days show the east wind that would bring smoke
vs 31% in a normal year — 13 points below normal

By trip day 08/28: 13% · 08/29: 21% · 08/30: 19%

By model gem global 21 members → 21% · gfs05 31 members → 16%

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.

Hover a dayto see the forecast we logged that morning and how much was known.

▲ Since 2026-08-10 the forecast has moved worse (+42 on the likely worst day) across 6 daily updates. Shading above shows source coverage, not this movement - hover a past day to see what we said that morning.

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

Why we think this

The dominant source is Grasshopper — 86,939 acres at 30% containment, 17 miles east — and in a record drought year at national preparedness level 5 with fully cured fuels, a fire that size almost certainly still produces smoke on Aug 28-30; late-August Cascade fires of this scale normally run into September and are ended by rain, not by crews. What decides the weekend is therefore transport, not source: the climatological default is onshore westerly flow, which sends Grasshopper's smoke east away from the house and is exactly why the local base rate is only 44 and why 28 sampled historical days in this window never exceeded 100. The bad mechanism is the reversal — a thermal trough or east gradient pushing smoke west through the Government Camp saddle, a genuine low gap in the crest directly above the house, then overnight drainage settling it into the Zigzag valley under a morning inversion; that this is live right now is visible in the 95 reading at Multorpor and the active NWS air-quality alert. Terrain is not the safety net it looks like: Mitchell (12.5 mi S), Austin (19.5 mi S, 2,016 acres, 0% contained), and Regan Hill (17.8 mi W) are all on the house's side of the crest, and Regan Hill sits in the direction the clean marine push comes from, so even a textbook onshore day is not automatically clean air.

A normal late August here is Clear - median AQI 44 across the last 4 years. On these exact dates: 2025: 57 · 2024: 36 · 2023: 39 · 2022: 39.

We are forecasting a worst day of 84, 40 points above that base rate. That departure rests entirely on the reasoning above; judge it for yourself.

What the bad version needs:
Grasshopper (86,939 acres, only 30% contained, 17 miles east) is still actively producing smoke on Aug 28 — the default expectation, since Cascade fires this size at this containment routinely burn into late September in a drought year and crews are rationed at national preparedness level 5. → A thermal trough or east-gradient event sets up over the Cascades, reversing the usual onshore flow. Smoke pours west through the Government Camp saddle — a low gap in the crest right above the house — instead of drifting east over the desert. → Overnight downslope drainage pulls that smoke down the Zigzag valley and a morning inversion caps it over Welches. It doesn't mix out, the next night reloads it, and the 24-hour average sits above 150 for two or three days running.
First visible signal: The Multorpor/Government Camp monitor on the AirNow app climbing over 100 two mornings in a row while Portland stays clean — that split means the smoke is coming over the crest, not up the valley. Alongside it, the NWS Portland forecast switching the Mt Hood corridor wind direction to east or northeast. - about 3 days ahead

Key drivers, and what would change our minds

Grasshopper Fire: 86,939 acres at 17 miles east, only 30% contained, near-certain to still be smoking on the trip dates
Wind direction is the whole forecast — westerly onshore flow keeps the house clean, an east-gradient event does not, and that is unforecastable 13 days out
The Government Camp saddle is a low gap in the Cascade crest directly upwind-east of the house; Mt Hood does not actually block this path
Three fires on the house's own side of the crest (Mitchell S, Austin S at 0% containment, Regan Hill W), so terrain shielding is not a valid assumption
Season running 1.63x normal at this exact location, with 95 AQI nine miles away today and an active NWS air-quality alert
Record drought, lowest-on-record snowpack, PL 5 nationally: new ignitions inside 15 miles over the next 13 days are more likely than usual and initial attack is resource-constrained

Rain: a quarter-inch or more falling on the west Cascades in the week before the trip — check any phone weather app for Welches. That drops my worst-day estimate by roughly half.
The Government Camp monitor on the AirNow app sitting under 50 for three straight days in the week before the trip while the fires are still burning — that means transport is genuinely not reaching this valley.
InciWeb showing Grasshopper over 80% contained with flat acreage by Aug 25.
The opposite: any east wind appearing in the weekend forecast for Government Camp on weather.gov, which would move me toward RECONSIDER.
A new named fire starting west of the Cascade crest within about 15 miles of Welches — that single event would roughly double my numbers, because there is no terrain between it and the house.
Any evacuation level posted for the Mt Hood corridor on the Clackamas County map, or a US-26 closure on TripCheck.

Fires within 60 miles

12.5 mi	Mitchell S	16 acres
17.4 mi	Grasshopper E	86,939 acres · 30% contained
17.8 mi	Regan Hill W	size not yet reported
19.5 mi	Austin S	2,016 acres · 0% contained
38.9 mi	High Lava NNW	1,211 acres · 8% contained
45.5 mi	Bench SSE	67,071 acres · 86% contained
49.5 mi	Beachcomb SSE	2,346 acres · 100% contained

The biggest hole in this forecast: 1 of the nearby fires (Regan Hill) have no size reported yet. Whether those are 300-acre creepers or 20,000-acre runners is most of the answer.

Pack this regardless

Two or three portable HEPA air purifiers rated for the bedrooms and main room — for twelve people this is the highest-value thing in the car. A box fan taped to a MERV-13 furnace filter works and costs $30.
A box of N95 or KN95 respirators, two per person. Cloth masks, bandanas, and surgical masks do nothing for wildfire smoke.
A cheap PM2.5 meter so you argue about a number instead of about how the air feels.
Rescue inhalers, allergy meds, and eye drops — and know before you arrive which people in the group are asthmatic, pregnant, over 65, or under 6.
An indoor-day kit: cards, board games, a projector or streaming plan. A rain plan and a smoke plan are the same plan.
A researched bail-out option — Cannon Beach or Manzanita is about 2.5 hours from the house and is almost always clean when the Cascades are smoky. Look up drive time and day-use options now, not at 9am on a bad Saturday.

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

Multorpor / Government Camp PM2.5, plus any PurpleAir sensor in Welches or Rhododendron - Over 100 for two consecutive mornings inside the 4 days before the trip — that's an established episode, not a passing puff. Under 50 for three straight days = stand down. (AirNow app or fire.airnow.gov (map layer: 'Fire and Smoke'))
Wind direction for the Mt Hood corridor on the trip dates - Any east or northeast wind in the Friday-Sunday forecast. West or northwest wind is the good sign. (weather.gov point forecast for Government Camp, OR)
Grasshopper Fire containment and growth - Still under 60% contained on Aug 25 with acreage still climbing = plan for smoke. Over 80% and flat acreage = the main source is winding down. (inciweb.wildfire.gov)
Austin Fire (19.5 mi south, 0% contained) and any NEW fire start inside 15 miles - A new named fire west of the crest within 15 miles of Welches — that one is on your side of the mountain and terrain will not help you. (inciweb.wildfire.gov and the Oregon Dept. of Forestry fire map)
Evacuation levels for the Mt Hood corridor - Any Level 1 within 10 miles of Welches, or a US-26 closure anywhere between Sandy and Government Camp. (Clackamas County evacuation map / clackamas.us and the ODOT TripCheck site for US-26)
Rain in the west Cascades before the trip - 0.25 inch or more of rain forecast between now and Aug 28 — that's the single best piece of good news you can get. (weather.gov / any phone weather app for Welches, OR)

Sandy	22.8 mi
Brightwood	17.5 mi
Welches	14.3 mi

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

If we wanted cleaner air, where would we go?

Ranked by how bad these dates have historically been at each place. The coast is not just cleaner today — it sits upwind of everything burning, so it only smokes during an east-wind reversal, which is the same event that would smoke out the house.

“Bad day / typical” is what the air actually did on Aug 26 – Sep 1 in 2022, 2023, 2024 and 2025 — 28 days per place. The first number is the bad day: one day in ten was worse than this. The second is the typical day, the middle of the range. We rank on the bad day rather than the typical one, because the bad day is what would spoil a weekend.

Both are converted onto the same scale as the “now” column, so every AQI figure in this table is comparable. That conversion matters more than it sounds: the model these come from runs about 2.5× high on the coast but close to true inland, so before correcting it the coast looked far worse than it is.

Place	Bad day / typical	Now	Official forecast	Next 5 days	Nearest fire
Newport coast	20 / 17	14 Clear	Good	▲ worsening	106 mi · Austin
Manzanita coast	22 / 21	23 Clear	Good	▲ worsening	87 mi · High Lava
Cannon Beach coast	23 / 20	23 Clear	Good	▲ worsening	88 mi · High Lava
Pacific City coast	23 / 20	23 Clear	Good	▲ worsening	98 mi · Austin
Astoria coast	26 / 23	17 Clear	Good	▲ worsening	84 mi · High Lava
Long Beach, WA coast	27 / 24	17 Clear	Good	▲ worsening	97 mi · High Lava
Welches / Mt Hood booked	37 / 28	67 Hazy	Sensitive groups	– steady	17 mi · Grasshopper
Silver Falls valley	45 / 33	23 Clear	Moderate	– steady	35 mi · Austin
Portland valley	48 / 38	37 Clear	Moderate	– steady	37 mi · High Lava
McMinnville valley	53 / 37	20 Clear	Moderate	– steady	61 mi · Austin
Bend east of crest	119 / 70	55 Hazy	Moderate	– steady	22 mi · Akawa Butte
Hood River east of crest	n/a	52 Hazy	Sensitive groups	– steady	21 mi · Grasshopper

What each column covers, and where it comes from

Field	Period it covers	What it is
Air right now	08/15/26 4:00 PDT	Nearest EPA/AirNow ground monitor to each place, within 45 miles airnow.gov
Official forecast	issued 08/15/26 by Oregon Dept. of Environmental Quality	Next published outlook for that reporting area — a human forecaster's call Oregon DEQ via AirNow
Next 5 days	today's model run, covering 2026-08-19	Direction only. Copernicus CAMS global air-quality model open-meteo.com
Bad day / typical	Aug 26 – Sep 1 in 2022, 2023, 2024, 2025 (28 days each)	CAMS reanalysis for those exact dates, then converted to the monitor scale open-meteo.com
Scale conversion	median of 14 daily model-vs-monitor pairs, 2026-07-31 to 2026-08-13	Median of daily model-vs-monitor ratios — the bias differs by place, from 0.375 on the coast to 1.056 inland AirNow daily archive
Nearest fire	queried Aug 15 5:00 AM	Perimeter polygons of fires over 100 acres, distance to the burned edge NIFC WFIGS

Every AQI figure above is on the ground-monitor scale — the same thing your phone shows. n/a means the model and the monitors disagree so sharply at that spot that we cannot honestly place it on that scale (steep terrain inside a coarse model grid cell — the Gorge is the usual culprit); those rows are sorted by today’s reading instead.

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 81, 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. 3 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 highest 24-hour-average US AQI for PM2.5 that touches any one of Aug 28, 29, or 30 at the Welches house — the worst single day of the trip, not the three-day average — expressed on the local monitor scale, i.e. the number a phone air-quality app would display, already calibrated from the raw model scale, with no further bias correction applied by me.”

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