Princeton/Rocky Hill, New Jersey · field elev 128 ft
Density Altitude at Princeton (39N)
Princeton sits at 128 ft, and even a typical July afternoon (87 °F) only lifts density altitude to about 1,941 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 | 31.0 | −1,730 ft | 40.5 | −1,068 ft |
| February | 32.8 | −1,603 ft | 43.0 | −897 ft |
| March | 40.3 | −1,082 ft | 50.9 | −362 ft |
| April | 51.0 | −355 ft | 62.9 | 432 ft |
| May | 60.6 | 281 ft | 72.8 | 1,069 ft |
| June | 69.8 | 878 ft | 81.7 | 1,630 ft |
| July | 74.9 | 1,203 ft | 86.7 | 1,941 ft |
| August | 72.9 | 1,076 ft | 84.9 | 1,829 ft |
| September | 66.1 | 639 ft | 78.3 | 1,417 ft |
| October | 54.3 | −135 ft | 66.4 | 659 ft |
| November | 44.2 | −815 ft | 55.3 | −68 ft |
| December | 36.1 | −1,373 ft | 45.5 | −726 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 39N
DENSITY ALTITUDE
Field elevation 128 ft — the air behaves like 1,959 ft.
- PRESSURE ALT
- 129 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 New Jersey fields
- 47N — Central Jersey Regional
Manville · elev 86 ft
- KTTN — Trenton Mercer
Trenton · elev 213 ft
- N87 — Trenton-Robbinsville
Robbinsville · elev 118 ft
- N51 — Solberg/Hunterdon
Readington · elev 190 ft
- KSMQ — Somerset
Somerville · elev 106 ft
- 3N6 — Old Bridge
Old Bridge · elev 87 ft
- N40 — Sky Manor
Pittstown · elev 560 ft
- N85 — Alexandria
Pittstown · elev 480 ft
Frequently asked questions
How high does density altitude get at 39N in summer?
On a typical July afternoon — around 87 °F at the nearest NOAA normals station — density altitude at Princeton reaches roughly 1,941 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 39N on an average day?
It swings with the seasons: from roughly −1,730 ft at the coldest month's average temperature to about 1,203 ft at the warmest month's — all from a constant field elevation of 128 ft. The month-by-month table above carries the full year.
What is the field elevation of Princeton?
128 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 39N (FAA), in Princeton/Rocky Hill, New Jersey.