Newton, Iowa · field elev 953 ft
Density Altitude at Newton Municipal-Earl Johnson Field (KTNU)
Newton Municipal-Earl Johnson Field sits at 953 ft, and even a typical July afternoon (85 °F) only lifts density altitude to about 2,817 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 | 19.2 | −1,536 ft | 28.0 | −909 ft |
| February | 23.7 | −1,214 ft | 33.0 | −559 ft |
| March | 36.1 | −344 ft | 46.4 | 359 ft |
| April | 48.8 | 520 ft | 60.4 | 1,286 ft |
| May | 60.6 | 1,299 ft | 71.4 | 1,992 ft |
| June | 70.6 | 1,942 ft | 81.2 | 2,607 ft |
| July | 74.2 | 2,170 ft | 84.6 | 2,817 ft |
| August | 72.0 | 2,031 ft | 82.5 | 2,688 ft |
| September | 64.3 | 1,538 ft | 76.2 | 2,295 ft |
| October | 51.5 | 700 ft | 62.5 | 1,422 ft |
| November | 37.0 | −282 ft | 46.7 | 379 ft |
| December | 25.2 | −1,107 ft | 33.6 | −517 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 KTNU
DENSITY ALTITUDE
Field elevation 953 ft — the air behaves like 2,842 ft.
- PRESSURE ALT
- 954 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 Iowa fields
- 8C2 — Sully Municipal
Sully · elev 922 ft
- KGGI — Grinnell Regional
Grinnell · elev 1,008 ft
- KPEA — Pella Municipal
Pella · elev 885 ft
- KOXV — Knoxville Municipal
Knoxville · elev 928 ft
- KIKV — Ankeny Regional
Ankeny · elev 910 ft
- KMIW — Marshalltown Municipal
Marshalltown · elev 975 ft
- 8C5 — Toledo Municipal
Toledo · elev 960 ft
- KDSM — Des Moines International
Des Moines · elev 958 ft
Frequently asked questions
How high does density altitude get at KTNU in summer?
On a typical July afternoon — around 85 °F at the nearest NOAA normals station — density altitude at Newton Municipal-Earl Johnson Field reaches roughly 2,817 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 KTNU on an average day?
It swings with the seasons: from roughly −1,536 ft at the coldest month's average temperature to about 2,170 ft at the warmest month's — all from a constant field elevation of 953 ft. The month-by-month table above carries the full year.
What is the field elevation of Newton Municipal-Earl Johnson Field?
953 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is KTNU (ICAO) / TNU (FAA), in Newton, Iowa.