Port Huron, Michigan · field elev 650 ft
Density Altitude at St Clair County International (KPHN)
St Clair County International sits at 650 ft, and even a typical July afternoon (81 °F) only lifts density altitude to about 2,243 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 | 25.4 | −1,472 ft | 30.9 | −1,084 ft |
| February | 26.9 | −1,366 ft | 33.3 | −916 ft |
| March | 35.2 | −784 ft | 42.2 | −302 ft |
| April | 46.1 | −38 ft | 54.2 | 504 ft |
| May | 57.7 | 735 ft | 66.7 | 1,320 ft |
| June | 67.6 | 1,378 ft | 76.4 | 1,937 ft |
| July | 73.3 | 1,741 ft | 81.3 | 2,243 ft |
| August | 71.8 | 1,646 ft | 79.7 | 2,144 ft |
| September | 65.0 | 1,211 ft | 73.1 | 1,729 ft |
| October | 53.2 | 438 ft | 60.5 | 919 ft |
| November | 41.0 | −384 ft | 46.9 | 16 ft |
| December | 31.2 | −1,063 ft | 36.0 | −728 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 KPHN
DENSITY ALTITUDE
Field elevation 650 ft — the air behaves like 2,225 ft.
- PRESSURE ALT
- 651 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
- D99 — Robertson Field
Richmond · elev 650 ft
- 39G — Avoca
Avoca · elev 726 ft
- 2E2 — Sharpe'S Strip
Emmett · elev 781 ft
- 76G — Marine City
Marine City · elev 614 ft
- D20 — Yale
Yale · elev 815 ft
- 57D — Ray Community
Ray · elev 632 ft
- 4Y8 — Para Field
Yale · elev 800 ft
- D98 — Romeo State
Romeo · elev 738 ft
Frequently asked questions
How high does density altitude get at KPHN in summer?
On a typical July afternoon — around 81 °F at the nearest NOAA normals station — density altitude at St Clair County International reaches roughly 2,243 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 KPHN on an average day?
It swings with the seasons: from roughly −1,472 ft at the coldest month's average temperature to about 1,741 ft at the warmest month's — all from a constant field elevation of 650 ft. The month-by-month table above carries the full year.
What is the field elevation of St Clair County International?
650 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is KPHN (ICAO) / PHN (FAA), in Port Huron, Michigan.