Seeley Lake, Montana · field elev 4,256 ft
Density Altitude at Seeley Lake (23S)
From a field elevation of 4,256 ft, a typical July afternoon at Seeley Lake (83 °F) raises density altitude to about 6,750 ft — solidly into the range where performance charts deserve a close read.
Typical density altitude by month
| Month | Avg temp °F | DA at avg temp | Afternoon high °F | DA on a typical afternoon |
|---|---|---|---|---|
| January | 22.0 | 2,798 ft | 32.0 | 3,485 ft |
| February | 24.7 | 2,985 ft | 36.5 | 3,788 ft |
| March | 32.5 | 3,519 ft | 45.1 | 4,359 ft |
| April | 40.2 | 4,035 ft | 53.6 | 4,911 ft |
| May | 49.4 | 4,640 ft | 64.5 | 5,603 ft ▲ |
| June | 56.4 | 5,091 ft | 72.2 | 6,081 ft ▲ |
| July | 63.7 | 5,553 ft | 83.2 | 6,750 ft ▲ |
| August | 62.8 | 5,496 ft | 82.9 | 6,732 ft ▲ |
| September | 54.6 | 4,975 ft | 72.8 | 6,118 ft ▲ |
| October | 42.4 | 4,181 ft | 56.0 | 5,065 ft ▲ |
| November | 30.5 | 3,383 ft | 39.6 | 3,995 ft |
| December | 21.8 | 2,784 ft | 30.6 | 3,390 ft |
▲ above 5,000 ft · ⚠ above 8,000 ft. These are planning references at standard pressure and dry air — afternoon humidity and low pressure both push the real number higher. Run today's values below.
Run today’s numbers for 23S
DENSITY ALTITUDE caution
Field elevation 4,256 ft — the air behaves like 6,738 ft.
- PRESSURE ALT
- 4,258 ft
- ISA DEVIATION
- —
- RULE-OF-THUMB DA
- —
- AIR DENSITY INDEX
- —
- AIR DENSITY
- —
- WATER · GRAINS/LB
- —
For training and reference · verify with official sources and your POH before flight · no tool on this site renders a go / no-go judgment
Nearby Montana fields
- S04 — Condon Usfs
Condon · elev 3,686 ft
- 52S — St Ignatius
St Ignatius · elev 3,006 ft
- RC0 — Rock Creek
Clinton · elev 3,547 ft
- 3U7 — Benchmark
Augusta · elev 5,434 ft
- KMSO — Missoula Montana
Missoula · elev 3,206 ft
- M26 — Drummond
Drummond · elev 4,245 ft
- S69 — Lincoln
Lincoln · elev 4,603 ft
- 7S0 — Ronan
Ronan · elev 3,086 ft
Frequently asked questions
How high does density altitude get at 23S in summer?
On a typical July afternoon — around 83 °F at the nearest NOAA normals station — density altitude at Seeley Lake reaches roughly 6,750 ft at standard pressure. Hotter-than-normal days, low pressure, and humidity all push it higher, so run the day's actual numbers before flying.
What is the density altitude at 23S on an average day?
It swings with the seasons: from roughly 2,784 ft at the coldest month's average temperature to about 5,553 ft at the warmest month's — all from a constant field elevation of 4,256 ft. The month-by-month table above carries the full year.
What is the field elevation of Seeley Lake?
4,256 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 23S (FAA), in Seeley Lake, Montana.