Freeport, Illinois · field elev 859 ft
Density Altitude at Albertus (KFEP)
Albertus sits at 859 ft, and even a typical July afternoon (82 °F) only lifts density altitude to about 2,567 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 | 19.6 | −1,626 ft | 27.9 | −1,034 ft |
| February | 23.7 | −1,332 ft | 32.6 | −704 ft |
| March | 35.4 | −509 ft | 44.9 | 141 ft |
| April | 47.3 | 303 ft | 58.2 | 1,026 ft |
| May | 59.1 | 1,085 ft | 69.9 | 1,782 ft |
| June | 69.0 | 1,724 ft | 79.3 | 2,374 ft |
| July | 72.4 | 1,941 ft | 82.4 | 2,567 ft |
| August | 70.3 | 1,807 ft | 80.7 | 2,461 ft |
| September | 62.6 | 1,313 ft | 74.3 | 2,061 ft |
| October | 50.4 | 510 ft | 61.5 | 1,241 ft |
| November | 37.1 | −392 ft | 46.0 | 215 ft |
| December | 25.6 | −1,196 ft | 33.3 | −655 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 KFEP
DENSITY ALTITUDE
Field elevation 859 ft — the air behaves like 2,542 ft.
- PRESSURE ALT
- 860 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 Illinois fields
- C55 — Ogle County
Mount Morris · elev 929 ft
- 1C8 — Cottonwood
Rockford · elev 741 ft
- KRFD — Chicago/Rockford International
Chicago/Rockford · elev 742 ft
- C73 — Dixon Municipal-Charles R Walgreen Field
Dixon · elev 785 ft
- KSFY — Tri-Township
Savanna · elev 616 ft
- KSQI — Whiteside County/Jos H Bittorf Field
Sterling/Rockfalls · elev 648 ft
- KRPJ — Rochelle Municipal/Koritz Field
Rochelle · elev 781 ft
- C77 — Poplar Grove
Poplar Grove · elev 857 ft
Frequently asked questions
How high does density altitude get at KFEP in summer?
On a typical July afternoon — around 82 °F at the nearest NOAA normals station — density altitude at Albertus reaches roughly 2,567 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 KFEP on an average day?
It swings with the seasons: from roughly −1,626 ft at the coldest month's average temperature to about 1,941 ft at the warmest month's — all from a constant field elevation of 859 ft. The month-by-month table above carries the full year.
What is the field elevation of Albertus?
859 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is KFEP (ICAO) / FEP (FAA), in Freeport, Illinois.