Mount Morris, Illinois · field elev 929 ft
Density Altitude at Ogle County (C55)
Ogle County sits at 929 ft, and even a typical July afternoon (85 °F) only lifts density altitude to about 2,782 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 | 21.7 | −1,387 ft | 30.1 | −791 ft |
| February | 25.7 | −1,102 ft | 34.7 | −471 ft |
| March | 37.6 | −270 ft | 47.8 | 423 ft |
| April | 49.4 | 530 ft | 61.1 | 1,302 ft |
| May | 61.1 | 1,302 ft | 73.0 | 2,064 ft |
| June | 70.5 | 1,906 ft | 82.0 | 2,628 ft |
| July | 73.0 | 2,064 ft | 84.5 | 2,782 ft |
| August | 71.0 | 1,938 ft | 82.8 | 2,677 ft |
| September | 64.0 | 1,489 ft | 76.8 | 2,304 ft |
| October | 52.1 | 710 ft | 63.9 | 1,483 ft |
| November | 38.7 | −195 ft | 48.2 | 450 ft |
| December | 27.2 | −995 ft | 35.1 | −443 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 C55
DENSITY ALTITUDE
Field elevation 929 ft — the air behaves like 2,813 ft.
- PRESSURE ALT
- 930 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
- C73 — Dixon Municipal-Charles R Walgreen Field
Dixon · elev 785 ft
- KFEP — Albertus
Freeport · elev 859 ft
- KRFD — Chicago/Rockford International
Chicago/Rockford · elev 742 ft
- KRPJ — Rochelle Municipal/Koritz Field
Rochelle · elev 781 ft
- 1C8 — Cottonwood
Rockford · elev 741 ft
- C82 — Bresson
Compton · elev 769 ft
- KSQI — Whiteside County/Jos H Bittorf Field
Sterling/Rockfalls · elev 648 ft
- C77 — Poplar Grove
Poplar Grove · elev 857 ft
Frequently asked questions
How high does density altitude get at C55 in summer?
On a typical July afternoon — around 85 °F at the nearest NOAA normals station — density altitude at Ogle County reaches roughly 2,782 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 C55 on an average day?
It swings with the seasons: from roughly −1,387 ft at the coldest month's average temperature to about 2,064 ft at the warmest month's — all from a constant field elevation of 929 ft. The month-by-month table above carries the full year.
What is the field elevation of Ogle County?
929 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is C55 (FAA), in Mount Morris, Illinois.