Seattle-Tacoma International to St. Louis Downtown Airport SEA → CPS
1,496 nautical miles (1,722 statute miles) east on a straight line, true course 099°, about 083° magnetic at the departure end (variation 16E). At 120 knots that is 9 h 25 min at the quickest height in today's winds (39,000 ft, a 39-knot tailwind), arriving about 5:16 am CDT (10:16 UTC), after sunset at the destination. For planning, not a briefing: the legal preflight briefing comes from Flight Service (1-800-WX-BRIEF) or the FAA's own tools. Airlines fly this pair: 6 flights in the DOT's last twelve reported months, the route's page.
The route the straight line, the warnings crossed, restrictions, pilot reports and the airports along the way · click a mark for its words
Green, blue, red and purple airport dots are the flying conditions reported there now (VFR, marginal VFR, IFR, low IFR); grey means no report. Red areas are SIGMETs, orange areas AIRMETs, hatched red areas temporary flight restrictions. Map tiles: OpenFreeMap, data © OpenStreetMap contributors.
Warnings the route crosses SIGMETs and AIRMETs whose area the line passes through or comes within 25 nm of
- SIGMET W70W: thunderstorms (a convective SIGMET) up to 32,000 ft, moving from the southwest at 40 knots, until 6:55 pm PDT (01:55 UTC). Over the route from 578 to 718 nm out.
as issued
WSUS33 KKCI 112355 MKCW WST 112355 CONVECTIVE SIGMET 70W VALID UNTIL 0155Z MT WY FROM 30SSW MLS-60WNW BFF-40SSE OCS-10S BPI-10S BIL-30SSW MLS AREA TS MOV FROM 22040KT. TOPS TO FL320.
- AIRMET ZULU 2C: moderate icing up to 14,000 ft. Over the route from 120 to 339 nm out.
- AIRMET SIERRA 1E: mountains obscured by cloud (due to mountains obscured by clouds, precipitation, mist). Over the route from 190 to 648 nm out.
- AIRMET TANGO 4W: moderate turbulence above 18,000 ft from 18,000 ft to 36,000 ft. Over the route from 259 to 848 nm out.
- AIRMET SIERRA 4E: low cloud or poor visibility (IFR conditions) (due to ceilings below 1,000 ft, visibility below 3 miles, precipitation, mist). Over the route from 299 to 698 nm out.
- AIRMET TANGO 4W: moderate turbulence below 18,000 ft up to 18,000 ft. Over the route from 489 to 678 nm out.
- AIRMET TANGO 1W: low-level wind shear (due to air speed loss or gain of 20 knots or more below 2,000 ft above the ground). Over the route from 549 to 658 nm out.
A SIGMET warns of weather hazardous to all aircraft; an AIRMET of weather that matters to small aircraft and to flying without instruments. "From 60 to 180 nm out" is measured along the route from SEA.
Pilot reports along the route within 50 nm of the line, last three hours, the serious ones first
Not fetched just now.
Winds aloft along the route, and the time en route the forecast for use 20:00–03:00 UTC · at 120 knots true airspeed
The eastbound cruising heights for this course (VFR: odd thousands plus 500 ft; above 18,000 ft the forecast levels), with the wind averaged along the line from the 15 forecast points nearest it (SEA, YKM, GEG, LWS, DLN, BIL, RAP, PIR, ONL, GRI, OMA, DSM, MKC, COU, STL). A plus sign is a headwind, a minus sign a tailwind.
| Height | Average wind | Head- or tailwind | Temperature | Ground speed | Time en route | Arrival |
|---|---|---|---|---|---|---|
| 5,500 ft | 160° at 5 kt | +5 kt | 13 °C | 115 kt | 13 h 01 min | 8:52 am CDT (13:52 UTC) |
| 7,500 ft | 190° at 4 kt | +2 kt | 7 °C | 118 kt | 12 h 41 min | 8:32 am CDT (13:32 UTC) |
| 9,500 ft | 220° at 7 kt | −1 kt | 4 °C | 121 kt | 12 h 22 min | 8:13 am CDT (13:13 UTC) |
| 11,500 ft | 220° at 12 kt | −3 kt | 1 °C | 123 kt | 12 h 10 min | 8:01 am CDT (13:01 UTC) |
| 13,500 ft | 230° at 14 kt | −5 kt | -3 °C | 125 kt | 11 h 58 min | 7:49 am CDT (12:49 UTC) |
| 15,500 ft | 230° at 16 kt | −7 kt | -7 °C | 127 kt | 11 h 47 min | 7:38 am CDT (12:38 UTC) |
| 17,500 ft | 230° at 18 kt | −9 kt | -11 °C | 129 kt | 11 h 36 min | 7:27 am CDT (12:27 UTC) |
| 18,000 ft FL180 | 230° at 18 kt | −9 kt | -12 °C | 129 kt | 11 h 36 min | 7:27 am CDT (12:27 UTC) |
| 24,000 ft FL240 | 240° at 26 kt | −16 kt | -22 °C | 136 kt | 11 h | 6:51 am CDT (11:51 UTC) |
| 30,000 ft FL300 | 240° at 32 kt | −18 kt | -35 °C | 138 kt | 10 h 50 min | 6:41 am CDT (11:41 UTC) |
| 34,000 ft FL340 | 240° at 41 kt | −27 kt | -41 °C | 147 kt | 10 h 11 min | 6:02 am CDT (11:02 UTC) |
| 39,000 ft FL390 | 250° at 48 kt | −39 kt | -47 °C | 159 kt | 9 h 25 min | 5:16 am CDT (10:16 UTC) |
Based on data from the 11th at 18:00 UTC; valid on the 12th at 00:00 UTC for use 20:00 to 03:00 UTC; temperatures above 24,000 ft are below zero. Heights are above sea level; a height is left out when the forecast has no wind for it over most of the line (the ground is higher). Ground speed is the airspeed less the headwind; the time en route is for the straight line and ignores climb, descent and routing around weather.
The forecast points as issued
| Point | From | 3,000 | 6,000 | 9,000 | 12,000 | 18,000 | 24,000 | 30,000 | 34,000 | 39,000 |
|---|---|---|---|---|---|---|---|---|---|---|
| SEA | used from 0 nm out; 25 nm from the line | 360/9 | 350/10 1° | 010/10 -5° | 030/20 -11° | 020/60 -17° | 010/86 -26° | 360/90 -40° | 010/68 -42° | 360/31 -43° |
| YKM | used from 50 nm out; 40 nm from the line | 030/16 | 020/18 0° | 030/30 -8° | 030/23 -13° | 020/40 -23° | 010/73 -29° | 010/54 -36° | 360/29 -37° | 330/16 -40° |
| GEG | used from 150 nm out; 48 nm from the line | 050/18 -2° | 060/19 -8° | L/V -11° | 160/11 -24° | 190/17 -31° | 200/19 -35° | 220/14 -37° | 250/11 -41° | |
| LWS | used from 199 nm out; 22 nm from the line | 010/5 | 050/14 -2° | 040/12 -6° | 160/7 -10° | 190/30 -22° | 200/54 -27° | 200/48 -35° | 210/40 -37° | 230/32 -41° |
| DLN | used from 349 nm out; 63 nm from the line | 080/10 -3° | 180/8 -3° | 180/23 -14° | 200/58 -22° | 200/80 -36° | 220/85 -41° | 230/81 -45° | ||
| BIL | used from 499 nm out; 66 nm from the line | 080/24 | 130/14 -1° | 180/33 0° | 210/43 -10° | 220/58 -21° | 200/55 -36° | 220/75 -44° | 240/83 -48° | |
| RAP | used from 698 nm out; 110 nm from the line | 120/15 12° | 180/22 11° | 220/26 5° | 230/35 -9° | 240/40 -22° | 240/50 -37° | 240/51 -41° | 240/47 -47° | |
| PIR | used from 898 nm out; 94 nm from the line | L/V 17° | 230/13 12° | 220/22 6° | 250/31 -9° | 250/34 -21° | 240/50 -35° | 230/61 -43° | 240/62 -51° | |
| ONL | used from 948 nm out; 73 nm from the line | 200/20 17° | 230/26 14° | 240/21 7° | 250/27 -9° | 260/32 -19° | 240/44 -34° | 240/56 -41° | 250/62 -51° | |
| GRI | used from 1097 nm out; 60 nm from the line | 210/31 19° | 240/21 14° | 240/17 6° | 260/27 -7° | 260/34 -18° | 240/45 -32° | 250/56 -40° | 260/62 -51° | |
| OMA | used from 1147 nm out; 19 nm from the line | 190/34 | 230/34 19° | 250/25 12° | 250/18 6° | 250/22 -7° | 250/28 -19° | 260/34 -32° | 260/39 -41° | 280/56 -51° |
| DSM | used from 1247 nm out; 73 nm from the line | 200/32 | 240/27 17° | 260/19 10° | 260/16 5° | 260/19 -7° | 240/22 -19° | 270/20 -32° | 270/38 -42° | 290/58 -53° |
| MKC | used from 1297 nm out; 78 nm from the line | 200/28 | 220/30 16° | 270/20 11° | 280/22 7° | 260/27 -6° | 270/27 -18° | 280/38 -32° | 270/38 -40° | 280/50 -52° |
| COU | used from 1347 nm out; 50 nm from the line | 210/16 | 220/19 15° | 240/33 10° | 250/29 7° | 280/21 -6° | 280/19 -18° | 300/34 -31° | 300/40 -42° | 300/60 -52° |
| STL | used from 1446 nm out; 12 nm from the line | 210/13 | 260/16 17° | 270/21 10° | 280/24 5° | 310/20 -7° | 320/22 -18° | 320/44 -33° | 320/59 -43° | 310/69 -51° |
The weather now: both ends and the airports along the way public airports with a weather report within 25 nm of the line, one for each stretch
| Airport | Where | Conditions | Wind | Visibility | Ceiling | Elevation | Reported |
|---|---|---|---|---|---|---|---|
| SEA Seattle, WA | departure | no report just now | 432 ft | ||||
| MWH Moses Lake, WA | 120 nm out, 8 nm northeast of the line, tower | no report just now | 1,188 ft | ||||
| LWS Lewiston, ID | 229 nm out, 22 nm southwest of the line, tower | no report just now | 1,442 ft | ||||
| HRF Hamilton, MT | 339 nm out, 4 nm east of the line | no report just now | 3,635 ft | ||||
| BZN Bozeman, MT | 469 nm out, 7 nm northeast of the line, tower | no report just now | 4,473 ft | ||||
| GCC Gillette, WY | 728 nm out, 6 nm northwest of the line | no report just now | 4,365 ft | ||||
| CUT Custer, SD | 818 nm out, 4 nm west of the line | no report just now | 5,619 ft | ||||
| ANW Ainsworth, NE | 987 nm out, 0 nm northeast of the line | no report just now | 2,588 ft | ||||
| OMA Omaha, NE | 1187 nm out, 13 nm north of the line, tower | no report just now | 984 ft | ||||
| ICL Clarinda, IA | 1237 nm out, 0 nm north of the line | no report just now | 995 ft | ||||
| SUS St Louis, MO | 1476 nm out, 8 nm southwest of the line, tower | no report just now | 463 ft | ||||
| CPS Cahokia/St Louis, IL | destination | no report just now | 412 ft |
The highest airport on this list sits at 5,619 ft; the ground between airports is higher still. Check the sectional chart for the terrain and the minimum safe heights along the line.
At CPS when you get there the forecast at the estimated arrival, 5:16 am CDT (10:16 UTC)
CPS has no terminal forecast; use the nearest airport that does.
Temporary flight restrictions on the line or within 25 nm of it
- 6/7634 CENTRALIA, MO, Monday, October 12, 2026 UTC 17 nm from the route, 1396 nm along the route · a hazard on the ground (fire-fighting, a chemical spill, rescue work) · today · ZKC
Daylight
Sunset at SEA 6:27 pm PDT (01:27 UTC), at CPS 6:27 pm CDT (23:27 UTC) (civil twilight ends 6:53 pm CDT (23:53 UTC)). At 120 knots the arrival at CPS is before sunrise there (7:06 am CDT (12:06 UTC)).
Each restriction opens the FAA's own page with the exact area, heights and times. Ordinary notices to air missions (closed runways, lights out) are not shown: the FAA's notice search is not open to sites like this one at this time.
Radar and forecast charts for the regions crossed government pictures, the latest each time the page loads
Sources: the Aviation Weather Center's data service (SIGMETs, AIRMETs, graphical AIRMETs, pilot reports, winds and temperatures aloft, observations and terminal forecasts), the National Weather Service radar, the Weather Prediction Center's charts, the FAA's temporary flight restriction list and shapes, and the FAA's airport file for the positions, elevations and magnetic variation. Fetched when the page is viewed and kept a few minutes. Each leg is the straight line between its two airports; airways, terrain and airspace are not considered. The airports in detail: Seattle-Tacoma International, St. Louis Downtown Airport.