Mt Hood · Aug 28-30 · 16 days out Updated Wed Aug 12, 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 three smaller ones sit to the south on the same side of the ridge, and all of them will still be burning during your trip — but the air at the house is clean right now because ocean air is pushing inland, which is the normal late-August pattern here. Our best guess is that one of your three days looks a little hazy, with a reading in the 40s or 50s: ugly sunsets, campfire smell, nothing that hurts a healthy person.

The real risk is a two-to-four day east-wind spell, which shows up maybe one weekend in five at this time of year and would funnel the east-side smoke straight down the US-26 corridor to you — and you will be able to see that coming about three days out.

Known now2 of 5 forecast sources already cover your dates
Next updateAug 13 — Deterministic weather
No horizonFire size and containment are observations, not forecasts — they can move this on any day
Decide byAug 25
What would change this
  • Evacuation zone at the housenone
  • US-26 open, Portland to Welchesopen
  • Air at Multorpor11 · 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 1054%Clear weekend AQI 0-50
Blue sky or low marine cloud, Mt Hood sharp in the morning, maybe a faint brown smudge on the eastern horizon at sunrise and a whiff of woodsmoke on the porch that's gone by ten. Everyone hikes, kids swim in the Salmon River.
nothing
3 in 1026%Hazy but fine AQI 50-100
Milky white sky, the mountain's outline soft or missing, a steady campfire smell that never clears. Sunsets go orange. Healthy adults feel nothing; the one person with asthma notices by evening.
Do the hiking before noon, keep windows shut overnight, run one purifier in whichever room the sensitive people sleep in.
1 in 1012%One smoky day AQI 100-150
One morning you can't see the ridge across the valley, everything smells like a fireplace, eyes sting on the porch, and the light stays yellow all day. The other two days are livable.
Move that one day indoors or drive west out of the valley — Portland, the Gorge's west end, the coast. No trail runs. N95s for anyone with asthma, heart trouble, or a pregnancy.
1 in 108%Real smoke episode AQI 150+
Two or three days of dim orange light at midday, visibility under a mile, headaches by afternoon, ash on the car. Fire traffic on US-26 and possibly a Level 1 'be ready' notice pinging phones.
Relocate the trip west of the Cascades or cut it short. Twelve people sealed in a cabin for three days is not the trip anyone booked.
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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 houseGrasshopper78,011 acres · 17.4 miAustin19.8 miMitchell12.5 miThe Narrows14.0 mifire perimetersmall fire, size knownlocated, size not reported10 milesEverything within 60 milesGrasshopperBenchTen MileBeachcombHigh LavaAustinMitchellThe NarrowsGorton Creek0579 Ten Mile0507
SandyBrightwoodWelchesGovernment Campan east wind would carry smoke from here20 mi40 miThe houseGrasshopper78,011 acres · 17.4 miBench67,071 acres · 45.5 miBeachcomb2,346 acres · 49.5 miAustin19.8 miMitchell12.5 miThe Narrows14.0 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, 3 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 25 - could reach 92
9% chance of a smoky day
Sat Aug 29
Clear
likely 26 - could reach 97
10% chance of a smoky day
Sun Aug 30
Clear
likely 28 - could reach 101
11% chance of a smoky day

The specific odds

All three days clear54%
At least one smoky day (100+)20%
Two or more smoky days9%
At least one bad day (150+)8%
US-26 closed during the trip2%
Evacuation level at Welches8%

The one thing that would bring smoke here

13%of 156 ensemble member-days show the east wind that would bring smoke
vs 31% in a normal year — 18 points below normal
By trip day 08/28: 13% · 08/29: 10% · 08/30: 15%
By model gem global 21 members → 14% · gfs05 31 members → 12%
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.

Wed Aug 12Thu 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 & containmentDeterministic weatherECMWF ensembleAir-quality / smoke modelAug 12 - 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 steady (+3 on the likely worst day) across 3 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
Aug 13Deterministic 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

Grasshopper at 78,000 acres and 20% containment on August 12 is a campaign fire; Oregon Cascade fires that size effectively never reach full containment before the first real fall rains in mid-to-late September, so it is close to certain it is still producing smoke on your dates. The reason the house reads 11 today is not the mountain — it's the marine push, W/NW flow and drizzle, and that pattern is the late-August default here, which is why four straight years of these calendar dates averaged a daily max of 10 to 16. The terrain argument people will make is wrong in a specific way worth naming: Mt Hood sits northeast of the house, while Grasshopper is due east across Barlow Pass, a 4,150 ft gap that US-26 itself runs through — and Mitchell, The Narrows, and Austin are all south of you on the same, west side of the crest with nothing in between, two of them uncontained. So the mechanism that ruins the weekend is a synoptic flip to offshore/east gradient, or a run on one of the small south-side fires, and neither is forecastable at 16 days; I'm therefore leaving the median near a hazy-but-harmless 48 and putting the weight into a fat but honest tail. New ignitions matter too — two of the fires on this list are days old and within 14 miles, and 16 more days of the driest fuels of the year is plenty of time for another one closer than any of them. The one thing keeping me from a scarier number is the averaging period: a smoky morning that clears by afternoon produces a 24-hour AQI in the 50s or 60s, not the 150 the sky looked like at 8am.

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 45, 33 points above that base rate. That departure rests entirely on the reasoning above; judge it for yourself.

What the bad version needs:
Grasshopper (78k acres, only 20% contained) keeps running through the driest three weeks of the year, and one of the uncontained west-side starts south of you — Austin at 719 acres and 0%, or Mitchell 12.5 miles away — makes a run of its own; by the 28th there are well over 100,000 acres of active fire within 20 miles. → An upper ridge builds over the Northwest and the surface pressure gradient flips offshore: east wind through the Columbia Gorge and, critically, straight through Barlow Pass — a 4,150 ft gap in the crest directly east of the house that US-26 runs through. Mt Hood is northeast of the house, not between it and the fire, so nothing blocks that corridor. → Smoke pours down the Zigzag/Sandy valley, pools under a nighttime inversion, and fails to mix out the next afternoon; the 24-hour average at Welches climbs past 100 and stays there for the two to four days the east-wind event lasts.
First visible signal: The NWS Portland point forecast for Government Camp switching from morning-only 'areas of smoke' to sustained east or northeast winds, and red/purple dots appearing WEST of the crest on the AirNow Fire and Smoke Map (airnow.gov/fires) — the Multorpor and Government Camp sensors are the tripwire, 8 miles from the house. - about 3 days ahead
Key drivers, and what would change our minds
  • Grasshopper: 78,011 acres at 20% containment, 17 miles east — near-certain to still be burning on the trip dates
  • Barlow Pass is a low gap directly east of the house; Mt Hood is northeast and does not shield this line
  • Three uncontained fires (Mitchell 12.5 mi, The Narrows 14 mi, Austin 19.8 mi) sit SOUTH of the house on the same side of the crest — no terrain barrier at all
  • Marine/onshore flow is the late-August default at Welches and is what's keeping the air at 11 today
  • Season running 1.52x normal over the last 30 days — elevated but not extreme
  • A 16-day lead time means zero skill on the offshore-gradient events that actually cause the bad days
  • The Multorpor or Government Camp sensor on airnow.gov/fires reading over 100 for most of a day at any point between now and the trip
  • Any forecast on weather.gov for Government Camp calling for east or northeast wind during Aug 27-30
  • Grasshopper's InciWeb page showing containment falling or acreage jumping past ~120,000
  • The Austin fire growing past a few thousand acres, or a brand-new fire appearing within about 20 miles on the Sandy/Clackamas (west) side
  • A Level 1 evacuation notice posted for Zigzag, Welches, or Brightwood
  • A soaking rain over western Oregon in the last week of August — that would push me toward a straight GO

Fires within 60 miles

12.5 miMitchell S16 acres
14.0 miThe Narrows SSW5 acres
17.4 miGrasshopper E78,011 acres · 20% contained
19.8 miAustin S719 acres · 0% contained
27.1 miGorton Creek NNEsize not yet reported
38.9 miHigh Lava NNW1,211 acres · 0% contained
45.5 miBench SSE67,071 acres · 86% contained

The biggest hole in this forecast: 1 of the nearby fires (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 — a dozen people, three or four each, they're cheap and useless if left at home
  • One or two portable HEPA air purifiers, or the parts for a box-fan-plus-MERV-13-filter (about $40 at any hardware store, works nearly as well)
  • Everyone's inhalers, allergy meds, and eye drops, plus a spare inhaler if anyone in the group has asthma
  • A downloaded rainy-day plan: cards, board games, a movie list — and one scouted indoor option west of Sandy
  • The AirNow app installed on at least three phones before you leave cell coverage
  • Extra drinking water and a full tank of gas in at least two cars, in case a road advisory changes plans quickly

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

  • Live PM2.5 at the Government Camp / Multorpor and Welches sensors - Either sensor sitting above 100 for 12+ hours on Aug 25-27 — that means the corridor is already open (https://fire.airnow.gov/)
  • Wind direction in the Government Camp point forecast - Any east or northeast wind forecast for Aug 27-30, especially over 10 mph (https://forecast.weather.gov/ (search Government Camp, OR))
  • Grasshopper fire size and containment - Containment stuck under 40%, or acreage jumping more than 15,000 in a single day (https://inciweb.wildfire.gov/ (search Grasshopper))
  • Austin and Mitchell fires — the ones south of you with no mountain in between - Austin over ~3,000 acres, or Mitchell growing past a few hundred acres (https://inciweb.wildfire.gov/ and Clackamas County Sheriff Facebook)
  • Evacuation levels for Zigzag / Welches / Brightwood - Any Level 1 for your zone — that's your cue to have cars packed, not to panic (https://www.oregon.gov/odf (Oregon evacuation map) or Clackamas County alerts)
  • HRRR-Smoke 48-hour surface smoke forecast, once inside two days - Visible plume crossing the crest onto the west slope (https://rapidrefresh.noaa.gov/hrrr/HRRRsmoke/)
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'm forecasting the US AQI for PM2.5 as a 24-hour average quantity — specifically, for each calendar day of the trip, the highest 24-hour-average AQI value overlapping that day, measured at the house in Welches, on the local monitor scale a phone app displays (the evidence pack's numbers are already bias-corrected and I applied no further correction). The headline numbers describe the single worst of the three days, Aug 28-30, not the average across them.”

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