Bonners Ferry, Idaho · field elev 2,337 ft
Density Altitude at Boundary County (65S)
Boundary County sits at 2,337 ft, and even a typical July afternoon (85 °F) only lifts density altitude to about 4,515 ft — heat still trims performance, but the field rarely turns high-and-hot.
Typical density altitude by month
| Month | Avg temp °F | DA at avg temp | Afternoon high °F | DA on a typical afternoon |
|---|---|---|---|---|
| January | 28.7 | 869 ft | 33.7 | 1,215 ft |
| February | 31.6 | 1,070 ft | 38.6 | 1,549 ft |
| March | 39.0 | 1,576 ft | 48.4 | 2,206 ft |
| April | 47.3 | 2,133 ft | 59.2 | 2,912 ft |
| May | 56.3 | 2,724 ft | 69.4 | 3,562 ft |
| June | 61.9 | 3,086 ft | 74.6 | 3,888 ft |
| July | 69.0 | 3,537 ft | 84.8 | 4,515 ft |
| August | 68.3 | 3,493 ft | 84.7 | 4,509 ft |
| September | 58.9 | 2,893 ft | 73.3 | 3,807 ft |
| October | 45.9 | 2,040 ft | 56.3 | 2,724 ft |
| November | 35.6 | 1,345 ft | 41.5 | 1,745 ft |
| December | 28.5 | 855 ft | 33.1 | 1,174 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 65S
DENSITY ALTITUDE
Field elevation 2,337 ft — the air behaves like 4,527 ft.
- PRESSURE ALT
- 2,338 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
- 1S1 — Eckhart International
Porthill · elev 1,758 ft
- 66S — Cavanaugh Bay
Coolin · elev 2,484 ft
- KSZT — Sandpoint
Sandpoint · elev 2,131 ft
- 67S — Priest Lake Usfs
Nordman · elev 2,611 ft
- 1S6 — Priest River
Priest River · elev 2,193 ft
- S77 — Magee
Coeur D'Alene · elev 3,002 ft
- KCOE — Coeur D'Alene
Coeur D'Alene · elev 2,320 ft
- S83 — Shoshone County
Kellogg · elev 2,227 ft
Frequently asked questions
How high does density altitude get at 65S in summer?
On a typical July afternoon — around 85 °F at the nearest NOAA normals station — density altitude at Boundary County reaches roughly 4,515 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 65S on an average day?
It swings with the seasons: from roughly 855 ft at the coldest month's average temperature to about 3,537 ft at the warmest month's — all from a constant field elevation of 2,337 ft. The month-by-month table above carries the full year.
What is the field elevation of Boundary County?
2,337 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 65S (FAA), in Bonners Ferry, Idaho.