Salmon, Idaho · field elev 4,044 ft
Density Altitude at Lemhi County (KSMN)
From a field elevation of 4,044 ft, a typical July afternoon at Lemhi County (86 °F) raises density altitude to about 6,678 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 | 19.6 | 2,366 ft | 28.2 | 2,962 ft |
| February | 26.0 | 2,811 ft | 35.8 | 3,479 ft |
| March | 37.5 | 3,593 ft | 49.5 | 4,385 ft |
| April | 45.2 | 4,104 ft | 58.7 | 4,977 ft |
| May | 54.0 | 4,676 ft | 68.3 | 5,581 ft ▲ |
| June | 61.0 | 5,123 ft | 75.7 | 6,038 ft ▲ |
| July | 69.0 | 5,625 ft | 86.3 | 6,678 ft ▲ |
| August | 66.7 | 5,481 ft | 84.8 | 6,588 ft ▲ |
| September | 57.4 | 4,894 ft | 74.3 | 5,952 ft ▲ |
| October | 44.6 | 4,064 ft | 58.4 | 4,958 ft |
| November | 31.2 | 3,167 ft | 40.8 | 3,813 ft |
| December | 20.9 | 2,457 ft | 28.9 | 3,010 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 KSMN
DENSITY ALTITUDE caution
Field elevation 4,044 ft — the air behaves like 6,660 ft.
- PRESSURE ALT
- 4,046 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 Idaho fields
- 4D2 — Hoodoo Meadows
Salmon · elev 8,262 ft
- 0U8 — May
May · elev 5,324 ft
- U00 — Leadore
Leadore · elev 6,029 ft
- U54 — Bernard Usfs
Bernard · elev 3,626 ft
- KLLJ — Challis
Challis · elev 5,076 ft
- 85U — Soldier Bar Usfs
Soldier Bar · elev 4,190 ft
- C53 — Lower Loon Creek
Challis · elev 4,200 ft
- I08 — Cabin Creek Usfs
Big Creek Ranger Station · elev 4,289 ft
Frequently asked questions
How high does density altitude get at KSMN in summer?
On a typical July afternoon — around 86 °F at the nearest NOAA normals station — density altitude at Lemhi County reaches roughly 6,678 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 KSMN on an average day?
It swings with the seasons: from roughly 2,366 ft at the coldest month's average temperature to about 5,625 ft at the warmest month's — all from a constant field elevation of 4,044 ft. The month-by-month table above carries the full year.
What is the field elevation of Lemhi County?
4,044 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is KSMN (ICAO) / SMN (FAA), in Salmon, Idaho.