St Johns, Michigan · field elev 717 ft
Density Altitude at Tripp Creek (39T)
Tripp Creek sits at 717 ft, and even a typical July afternoon (83 °F) only lifts density altitude to about 2,443 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 | 24.2 | −1,474 ft | 30.6 | −1,021 ft |
| February | 25.8 | −1,360 ft | 33.0 | −853 ft |
| March | 34.9 | −721 ft | 43.7 | −117 ft |
| April | 46.6 | 79 ft | 56.9 | 765 ft |
| May | 58.8 | 890 ft | 69.3 | 1,569 ft |
| June | 68.8 | 1,537 ft | 78.9 | 2,176 ft |
| July | 72.8 | 1,792 ft | 83.2 | 2,443 ft |
| August | 71.0 | 1,678 ft | 81.3 | 2,325 ft |
| September | 63.9 | 1,222 ft | 74.8 | 1,918 ft |
| October | 52.2 | 454 ft | 61.7 | 1,079 ft |
| November | 40.0 | −369 ft | 47.3 | 127 ft |
| December | 30.0 | −1,063 ft | 36.0 | −645 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 39T
DENSITY ALTITUDE
Field elevation 717 ft — the air behaves like 2,431 ft.
- PRESSURE ALT
- 718 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 Michigan fields
- M99 — Shady Lane
St Johns · elev 680 ft
- 3S5 — Schiffer Acres
St Johns · elev 741 ft
- 97G — Glowacki
St Johns · elev 775 ft
- 4M4 — Shady Lawn Field
Bannister · elev 683 ft
- C57 — Millers Landing
Elsie · elev 757 ft
- 3F5 — Forest Hill
Westphalia · elev 772 ft
- C88 — Tkaczyk Field
Oakley · elev 727 ft
- 41G — University Airpark
Bath · elev 856 ft
Frequently asked questions
How high does density altitude get at 39T in summer?
On a typical July afternoon — around 83 °F at the nearest NOAA normals station — density altitude at Tripp Creek reaches roughly 2,443 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 39T on an average day?
It swings with the seasons: from roughly −1,474 ft at the coldest month's average temperature to about 1,792 ft at the warmest month's — all from a constant field elevation of 717 ft. The month-by-month table above carries the full year.
What is the field elevation of Tripp Creek?
717 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 39T (FAA), in St Johns, Michigan.