Libby, Montana · field elev 2,605 ft
Density Altitude at Libby (S59)
Libby sits at 2,605 ft, and even a typical July afternoon (87 °F) only lifts density altitude to about 4,944 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 | 26.6 | 1,058 ft | 32.2 | 1,445 ft |
| February | 29.3 | 1,245 ft | 37.4 | 1,801 ft |
| March | 37.2 | 1,787 ft | 47.9 | 2,504 ft |
| April | 44.6 | 2,285 ft | 58.1 | 3,171 ft |
| May | 54.3 | 2,924 ft | 69.1 | 3,871 ft |
| June | 60.6 | 3,331 ft | 75.7 | 4,283 ft |
| July | 67.9 | 3,796 ft | 86.5 | 4,944 ft |
| August | 66.2 | 3,688 ft | 84.2 | 4,805 ft |
| September | 56.0 | 3,035 ft | 71.9 | 4,047 ft |
| October | 43.5 | 2,212 ft | 54.7 | 2,950 ft |
| November | 32.7 | 1,480 ft | 38.4 | 1,868 ft |
| December | 26.1 | 1,023 ft | 31.2 | 1,377 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 S59
DENSITY ALTITUDE
Field elevation 2,605 ft — the air behaves like 4,974 ft.
- PRESSURE ALT
- 2,607 ft
- ISA DEVIATION
- —
- RULE-OF-THUMB DA
- —
- AIR DENSITY INDEX
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- 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
- 57S — Troy
Troy · elev 2,017 ft
- KTHM — Thompson Falls
Thompson Falls · elev 2,467 ft
- 88M — Eureka
Eureka · elev 2,672 ft
- S27 — Kalispell City
Kalispell · elev 2,932 ft
- 58S — Whitefish
Whitefish · elev 3,066 ft
- KGPI — Glacier Park International
Kalispell · elev 2,977 ft
- S09 — Hot Springs
Hot Springs · elev 2,763 ft
- S34 — Plains
Plains · elev 2,467 ft
Frequently asked questions
How high does density altitude get at S59 in summer?
On a typical July afternoon — around 87 °F at the nearest NOAA normals station — density altitude at Libby reaches roughly 4,944 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 S59 on an average day?
It swings with the seasons: from roughly 1,023 ft at the coldest month's average temperature to about 3,796 ft at the warmest month's — all from a constant field elevation of 2,605 ft. The month-by-month table above carries the full year.
What is the field elevation of Libby?
2,605 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is S59 (FAA), in Libby, Montana.