Mountain City, Tennessee · field elev 2,241 ft
Density Altitude at Johnson County (6A4)
Johnson County sits at 2,241 ft, and even a typical July afternoon (82 °F) only lifts density altitude to about 4,227 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 | 34.2 | 1,130 ft | 45.5 | 1,894 ft |
| February | 37.1 | 1,328 ft | 48.8 | 2,114 ft |
| March | 44.0 | 1,794 ft | 56.7 | 2,632 ft |
| April | 53.0 | 2,390 ft | 66.8 | 3,280 ft |
| May | 61.3 | 2,929 ft | 73.9 | 3,727 ft |
| June | 68.1 | 3,362 ft | 79.9 | 4,098 ft |
| July | 71.2 | 3,558 ft | 82.0 | 4,227 ft |
| August | 70.3 | 3,501 ft | 81.4 | 4,191 ft |
| September | 64.7 | 3,147 ft | 76.9 | 3,913 ft |
| October | 54.5 | 2,489 ft | 68.2 | 3,369 ft |
| November | 44.6 | 1,834 ft | 58.0 | 2,716 ft |
| December | 37.6 | 1,362 ft | 48.9 | 2,120 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 6A4
DENSITY ALTITUDE
Field elevation 2,241 ft — the air behaves like 4,227 ft.
- PRESSURE ALT
- 2,242 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 Tennessee fields
- 0A9 — William B Greene Jr Regional
Elizabethton · elev 1,593 ft
- 0A4 — Johnson City
Johnson City · elev 1,550 ft
- KTRI — Tri-Cities
Bristol/Johnson/Kingsport · elev 1,519 ft
- KGCY — Greeneville Municipal
Greeneville · elev 1,608 ft
- KRVN — Hawkins County
Rogersville · elev 1,255 ft
- KMOR — Moore-Murrell
Morristown · elev 1,313 ft
- 3A2 — The New Tazewell/Wayne Coffey Municipal
Tazewell · elev 1,179 ft
- KGKT — Gatlinburg-Pigeon Forge
Sevierville · elev 1,014 ft
Frequently asked questions
How high does density altitude get at 6A4 in summer?
On a typical July afternoon — around 82 °F at the nearest NOAA normals station — density altitude at Johnson County reaches roughly 4,227 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 6A4 on an average day?
It swings with the seasons: from roughly 1,130 ft at the coldest month's average temperature to about 3,558 ft at the warmest month's — all from a constant field elevation of 2,241 ft. The month-by-month table above carries the full year.
What is the field elevation of Johnson County?
2,241 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 6A4 (FAA), in Mountain City, Tennessee.