In 1941 the planetary Kp peaked at 9.0 (G5) on 1 March 1941: 100 storm nights over the year, and 9.3% of its three-hour intervals at storm level.
| Month | Max Kp | Peak day | Storm nights | By class | At storm level | Avg Kp |
|---|---|---|---|---|---|---|
| January | 5.7 | 17 | 6 | G1×4G2×2 | 5.2% | 2.5 |
| February | 5.7 | 21 | 11 | G1×8G2×3 | 10.3% | 2.9 |
| March | 9.0 | 1 | 17 | G1×10G2×3G3×1G4×2G5×1 | 25.4% | 3.4 |
| April | 6.7 | 24 | 10 | G1×7G2×2G3×1 | 9.2% | 2.4 |
| May | 5.3 | 17 | 4 | G1×4 | 3.2% | 2.1 |
| June | 6.0 | 10 | 6 | G1×3G2×3 | 4.2% | 2.0 |
| July | 9.0 | 5 | 6 | G1×2G2×2G3×1G5×1 | 10.1% | 2.3 |
| August | 8.3 | 4 | 10 | G1×6G2×3G4×1 | 12.5% | 2.3 |
| September | 9.0 | 19 | 13 | G1×6G2×5G4×1G5×1 | 12.5% | 2.7 |
| October | 6.7 | 11 | 4 | G2×2G3×2 | 4.4% | 2.0 |
| November | 7.7 | 1 | 10 | G1×7G2×2G4×1 | 11.3% | 2.4 |
| December | 7.7 | 1 | 3 | G1×1G2×1G4×1 | 4.0% | 2.0 |
In the hall of storms: 19 September 1941 · Kp 9.0 →
All-time record: Kp 9.0 — reached on 27 days, most recently 2024-05-11.
Ranked from the data: peak Kp, then intervals spent at 9.0. Nicknames and reach notes only where documented.
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