The largest fire near you sits on the far side of Mt Hood, and late-August wind here almost always blows from the ocean toward the high desert, which carries that fire's smoke away from the house rather than toward it. The monitor eight miles from the house currently reads 11 — clean — even with a 64,000-acre fire burning seventeen miles to the east, which tells you the everyday geometry is working in your favor.
The ways this goes wrong are a two-or-three-day east-wind spell that reverses the flow and pours smoke down the Zigzag–Sandy valley, or a brand-new fire starting on your side of the mountains during the next two and a half weeks; together those are roughly a one-in-five chance of at least one genuinely smoky day.
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 1053% | Clear weekend AQI 0-50 Mt Hood sharp against blue sky, no smell of smoke, kids and dogs outside all day, sunsets normal. | nothing |
| 3 in 1026% | Hazy but fine AQI 50-100 Milky white sky, the mountain looks washed out and distant, faint campfire smell in the early morning that burns off by noon, orange sun at sunset. Healthy people notice nothing physical. | Close windows overnight and run the AC or a filter box in the sleeping rooms; anyone with asthma keeps an inhaler handy. The trip is otherwise unchanged. |
| 1 in 1012% | One smoky day AQI 100-150 You cannot see Mt Hood at all, visibility down the highway is a couple of miles, clear smoke smell indoors and out, scratchy throat and stinging eyes after an hour outside, headlights on at midday. | Move that day indoors — no hikes, no river, no long stretches on the deck. Run a box-fan filter in the main room, keep windows shut, and swap the outdoor plan for the indoor one. Kids, anyone pregnant, anyone with asthma or heart trouble should stay in. |
| 1 in 109% | Real smoke episode AQI 150+ Grey-brown air with the sun a dim orange disc, ash flecks on car hoods, smoke you can taste, everyone coughing, indoor air noticeably hazy in the far corner of the room. Possible evacuation notices somewhere in the corridor and possible highway delays. | This is when people with lungs, hearts, kids, or pregnancy should leave or not come; the rest of the group is stuck indoors for the duration. Cancel or shorten if the forecast shows it two-plus days out, and have a bail-out route and a place to go in Portland. |
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.
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.
Shading shows how many sources cover the trip, not forecast history. Only today has a forecast on record so far; each morning adds one, and hovering a past day will show exactly what we said that day.
| 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 |
| Aug 15 | ECMWF ensemble (51 members) wind direction, the sharpest ensemble · reaches 13 days out |
| Aug 13 | 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 |
The dominant fire, Grasshopper at 63,659 acres and 23% contained, sits at bearing 94 degrees — due east, on the dry side of the Cascade crest near the White River/Wapinitia country — and the prevailing late-August flow in northwest Oregon is onshore west-to-east, which carries that plume away from Welches into the high desert; the proof is that the Multorpor monitor reads 11 today with that fire only 17 miles away. Mt Hood's 11,250-foot summit does not shield anything by itself — smoke travels in the boundary layer and moves through passes and drainages, and Barlow Pass and the Zigzag–Sandy valley open straight toward the fire — so the real protection is wind direction, not rock, and wind direction reverses in offshore east-wind events that typically last one to three days in late August. I also do not credit a terrain story at all for the Mitchell, Narrows, Austin and Clackamas fires, which are 12 to 20 miles south and southwest of the house on the same west slope with nothing in between; their acreages are unreported, which caps how much weight I put on them but also means I cannot rule them out, and a southerly push ahead of a weak trough would run their smoke straight up the corridor. Against that, a large Oregon fire at this size and containment on August 10 will almost certainly still be smoldering on August 28 — these do not go out before September rain — so I am not banking on the fire being gone, only on the wind staying honest.
A normal late August here is Clear - median AQI 19 across the last 4 years. On these exact dates: 2025: 25 · 2024: 16 · 2023: 17 · 2022: 17.
We are forecasting a worst day of 42, 23 points above that base rate. That departure rests entirely on the reasoning above; judge it for yourself.
| 17.4 mi | Grasshopper E | 63,659 acres · 23% contained |
| 19.7 mi | Clackamas Fire S | 663 acres |
| 39.2 mi | High Lava N | 879 acres · 0% contained |
| 45.5 mi | Bench SSE | 67,071 acres · 86% contained |
| 49.5 mi | Beachcomb SSE | 2,346 acres · 100% contained |
| 56.2 mi | 0683 Mud Springs SE | 85 acres |
| 56.7 mi | Ten Mile SE | 4,834 acres · 100% contained |
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.
| Sandy | None mi |
| Brightwood | None mi |
| Welches | None mi |
Distance from each point on the drive in to the nearest fire. TripCheck is the authority on closures.
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 highest 24-hour-average US AQI for PM2.5 that touches any one of August 28, 29, or 30, 2026, measured at the Welches / Mt Hood Village house — on the local monitor scale, meaning the number a normal phone air-quality app would display, with no further bias correction applied by me. It is the worst single day of the three, not the three-day average, and not a brief hourly spike.”
Updated daily at 5am. A convenience, not an authority -
if officials issue an evacuation order, follow it.