Fairfield, Montana · field elev 3,991 ft
Density Altitude at Fairfield (5U5)
From a field elevation of 3,991 ft, a typical July afternoon at Fairfield (80 °F) raises density altitude to about 6,217 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 | 26.1 | 2,752 ft | 35.7 | 3,406 ft |
| February | 26.8 | 2,800 ft | 36.4 | 3,453 ft |
| March | 34.3 | 3,312 ft | 44.8 | 4,012 ft |
| April | 42.2 | 3,840 ft | 52.8 | 4,534 ft |
| May | 51.5 | 4,450 ft | 62.3 | 5,140 ft ▲ |
| June | 58.5 | 4,899 ft | 69.5 | 5,591 ft ▲ |
| July | 66.5 | 5,404 ft | 79.7 | 6,217 ft ▲ |
| August | 65.5 | 5,342 ft | 79.0 | 6,174 ft ▲ |
| September | 56.3 | 4,759 ft | 68.5 | 5,529 ft ▲ |
| October | 44.6 | 3,999 ft | 55.3 | 4,695 ft |
| November | 33.8 | 3,278 ft | 42.7 | 3,873 ft |
| December | 26.6 | 2,786 ft | 35.3 | 3,379 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 5U5
DENSITY ALTITUDE caution
Field elevation 3,991 ft — the air behaves like 6,235 ft.
- PRESSURE ALT
- 3,993 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
- KCII — Choteau
Choteau · elev 3,947 ft
- 5U1 — Dutton
Dutton · elev 3,699 ft
- 3U5 — Augusta
Augusta · elev 4,145 ft
- KGTF — Great Falls International
Great Falls · elev 3,680 ft
- S01 — Conrad
Conrad · elev 3,548 ft
- 3U7 — Benchmark
Augusta · elev 5,434 ft
- 7S7 — Valier
Valier · elev 3,826 ft
- S69 — Lincoln
Lincoln · elev 4,603 ft
Frequently asked questions
How high does density altitude get at 5U5 in summer?
On a typical July afternoon — around 80 °F at the nearest NOAA normals station — density altitude at Fairfield reaches roughly 6,217 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 5U5 on an average day?
It swings with the seasons: from roughly 2,752 ft at the coldest month's average temperature to about 5,404 ft at the warmest month's — all from a constant field elevation of 3,991 ft. The month-by-month table above carries the full year.
What is the field elevation of Fairfield?
3,991 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 5U5 (FAA), in Fairfield, Montana.