TABLE 4 ESTIMATES OF 13-MONTH SMOOTH SOLAR ACTIVITY FOR BALANCE OF CYCLE 24 WITH A MEAN CYCLE GIVEN FOR CYCLE 25 TIME SUNSPOT NUMBERS GEOMAGNETIC INDEX (Ap) PERCENTILE PERCENTILE 95.0% 50% 5.0% 95.0% 50% 5.0% 2018.6670 SEP 8.4 6.2 3.1 7.3 6.8 6.2 2018.7503 OCT 9.3 6.0 0.8 8.2 7.0 5.5 2018.8337 NOV 10.8 6.3 0.0 8.9 7.2 5.3 2018.9170 DEC 11.5 6.3 0.0 9.1 7.3 5.3 2019.0003 JAN 12.4 5.9 0.0 9.2 7.5 5.4 2019.0837 FEB 12.3 5.4 0.0 9.7 7.8 5.7 2019.1670 MAR 12.5 4.9 0.0 10.6 8.3 6.1 2019.2503 APR 13.9 4.8 0.0 11.4 8.6 6.4 2019.3337 MAY 14.8 4.7 0.0 11.7 8.8 6.5 2019.4170 JUN 15.4 4.6 0.0 11.4 8.5 6.3 2019.5003 JUL 14.6 4.5 0.0 11.0 8.1 5.9 2019.5837 AUG 12.8 4.2 0.0 10.6 7.8 5.5 2019.6670 SEP 11.7 3.9 0.0 10.0 7.8 5.7 2019.7503 OCT 11.0 3.5 0.0 9.7 7.8 5.7 2019.8337 NOV 9.8 3.1 0.0 9.6 7.7 5.6 2019.9170 DEC 9.8 3.1 0.0 9.6 7.7 5.6 2020.0003 JAN 10.8 3.8 0.7 9.8 7.8 5.6 2020.0837 FEB 12.7 4.9 1.4 10.1 7.9 5.8 2020.1670 MAR 14.4 5.9 2.0 10.2 8.1 6.1 2020.2503 APR 17.0 6.9 2.8 10.4 8.1 6.2 2020.3337 MAY 19.9 8.2 3.2 10.5 8.2 6.2 2020.4170 JUN 24.7 9.7 3.9 10.6 8.3 5.9 2020.5003 JUL 28.3 11.3 5.0 10.7 8.4 5.8 2020.5837 AUG 32.0 13.0 5.4 11.0 8.6 5.7 2020.6670 SEP 37.6 15.1 5.5 11.3 8.9 5.6 2020.7503 OCT 44.7 17.4 5.8 11.7 9.3 5.8 2020.8337 NOV 55.2 20.3 5.7 12.2 9.6 6.2 2020.9170 DEC 64.2 23.6 5.9 13.1 9.9 6.5 2021.0003 JAN 71.2 26.8 7.0 14.2 10.2 6.3 2021.0837 FEB 81.4 30.5 7.1 14.6 10.4 6.3 2021.1670 MAR 92.7 34.5 7.1 14.8 10.5 6.2 2021.2503 APR 102.8 38.5 7.9 15.3 10.7 6.2 2021.3337 MAY 115.2 42.8 8.0 16.5 11.0 6.2 2021.4170 JUN 129.8 47.9 8.6 17.4 11.3 6.3 2021.5003 JUL 140.0 53.1 9.7 17.6 11.4 6.3 2021.5837 AUG 146.9 58.6 11.4 17.7 11.6 6.4 2021.6670 SEP 154.0 64.2 12.9 17.5 11.8 6.3 2021.7503 OCT 161.9 69.5 15.1 17.1 11.9 6.3 2021.8337 NOV 170.6 74.7 16.4 17.0 12.0 6.4 2021.9170 DEC 180.0 80.0 16.5 17.4 12.1 6.6 2022.0003 JAN 188.8 85.8 18.7 17.3 12.2 6.8 2022.0837 FEB 196.4 91.6 20.6 16.3 12.3 7.2 2022.1670 MAR 204.4 97.4 22.3 16.4 12.5 7.3 2022.2503 APR 209.2 103.2 24.2 17.0 12.7 7.4 2022.3337 MAY 215.7 108.6 25.1 17.6 12.9 7.6 2022.4170 JUN 217.1 113.4 26.1 18.1 13.4 8.0 2022.5003 JUL 217.6 118.0 27.1 18.8 13.7 8.2 2022.5837 AUG 222.9 121.9 27.8 18.8 13.8 8.2 2022.6670 SEP 225.4 125.2 28.5 18.8 13.8 8.4 2022.7503 OCT 227.9 128.9 28.5 19.0 13.9 8.6 2022.8337 NOV 231.1 132.6 27.9 19.3 14.1 9.1 2022.9170 DEC 233.5 136.4 27.3 19.7 14.1 9.7 2023.0003 JAN 239.9 139.8 28.0 19.8 14.0 10.3 2023.0837 FEB 247.5 142.8 29.0 19.9 13.8 9.9 2023.1670 MAR 252.4 145.7 31.1 20.1 13.8 9.8 2023.2503 APR 256.6 149.1 34.3 20.5 13.7 9.3 2023.3337 MAY 261.3 151.8 36.2 21.3 13.6 8.9 2023.4170 JUN 264.7 153.7 38.5 21.0 13.4 8.6 2023.5003 JUL 266.8 155.0 42.4 19.8 13.2 8.7 2023.5837 AUG 267.9 155.2 46.7 19.1 13.1 8.7 2023.6670 SEP 269.4 155.8 51.3 18.6 12.9 9.0 2023.7503 OCT 269.0 157.1 53.5 18.1 12.8 9.2 2023.8337 NOV 267.9 157.9 55.6 18.0 12.7 9.2 2023.9170 DEC 269.2 158.5 59.5 17.8 12.7 9.1 2024.0003 JAN 268.7 157.1 62.2 17.6 13.0 9.1 2024.0837 FEB 263.1 154.9 66.0 17.4 13.3 9.1 2024.1670 MAR 256.4 153.6 68.7 17.4 13.4 8.9 2024.2503 APR 250.4 153.0 71.3 18.0 13.3 8.5 2024.3337 MAY 246.9 152.9 73.2 18.9 13.4 8.8 2024.4170 JUN 245.1 152.6 72.9 20.5 13.8 9.3 2024.5003 JUL 243.5 152.1 72.1 21.9 14.0 9.4 2024.5837 AUG 242.2 151.4 73.3 22.5 14.2 9.5 2024.6670 SEP 240.1 150.4 76.5 23.6 14.4 9.7 2024.7503 OCT 238.5 149.7 76.7 24.1 14.6 9.9 2024.8337 NOV 236.5 148.7 75.1 23.4 14.6 10.1 2024.9170 DEC 235.3 147.5 74.0 23.3 14.6 10.3 2025.0003 JAN 232.9 146.2 74.9 22.5 14.5 10.5 2025.0837 FEB 228.6 143.8 75.7 20.6 14.5 10.4 2025.1670 MAR 223.5 140.6 73.7 20.9 14.6 10.6 2025.2503 APR 219.3 137.7 72.9 21.6 14.7 10.4 2025.3337 MAY 214.6 135.6 74.5 21.7 14.7 9.7 2025.4170 JUN 208.5 133.6 76.2 21.1 14.7 9.4 2025.5003 JUL 203.6 130.8 74.2 20.5 14.6 9.4 2025.5837 AUG 197.9 127.8 70.9 20.4 14.6 9.4 2025.6670 SEP 193.5 125.5 69.3 21.2 14.9 9.4 2025.7503 OCT 191.9 123.9 68.8 22.2 15.2 9.4 2025.8337 NOV 186.7 121.5 65.5 22.4 15.4 9.4 2025.9170 DEC 183.8 118.6 58.3 22.4 15.7 9.3 2026.0003 JAN 182.1 115.7 56.8 22.4 15.9 9.2 2026.0837 FEB 177.2 113.0 58.9 22.0 15.9 8.9 2026.1670 MAR 171.6 110.8 57.6 21.1 16.0 9.1 2026.2503 APR 165.9 108.9 54.5 21.3 15.9 9.3 2026.3337 MAY 160.3 107.2 52.9 21.5 16.1 10.0 2026.4170 JUN 155.6 105.0 51.5 21.6 16.4 10.5 2026.5003 JUL 152.3 102.4 49.0 21.0 16.5 10.6 2026.5837 AUG 147.1 99.3 46.2 20.2 16.3 10.8 2026.6670 SEP 138.1 95.8 44.6 19.7 16.1 10.9 2026.7503 OCT 129.8 92.0 44.0 20.2 15.8 11.1 2026.8337 NOV 128.6 88.9 44.4 20.2 15.6 11.9 2026.9170 DEC 127.1 86.2 42.9 20.6 15.6 11.7 2027.0003 JAN 122.8 83.7 40.5 21.1 15.7 11.5 2027.0837 FEB 118.3 81.3 40.7 20.8 15.5 11.7 2027.1670 MAR 113.6 78.7 39.7 20.9 15.2 11.4 2027.2503 APR 108.2 76.0 37.9 21.2 14.9 11.1 2027.3337 MAY 107.3 73.5 36.4 21.4 14.6 10.7 2027.4170 JUN 108.3 70.9 34.0 22.0 14.3 9.9 2027.5003 JUL 106.8 68.1 31.6 22.6 14.1 9.1 2027.5837 AUG 105.4 65.3 27.8 23.3 14.0 9.3 2027.6670 SEP 103.0 63.4 24.8 23.8 14.0 9.4 2027.7503 OCT 99.0 61.4 22.9 24.1 14.1 9.3 2027.8337 NOV 95.1 59.4 19.9 23.9 14.0 9.4 2027.9170 DEC 91.8 57.2 17.3 23.4 13.9 9.6 2028.0003 JAN 91.0 54.9 15.8 22.5 13.7 9.7 2028.0837 FEB 89.9 52.7 14.5 21.5 13.6 9.9 2028.1670 MAR 86.9 50.6 13.2 21.0 13.7 9.8 2028.2503 APR 83.0 48.5 13.0 20.6 13.8 9.7 2028.3337 MAY 77.9 46.1 13.2 20.3 14.0 9.8 2028.4170 JUN 76.2 44.3 12.6 19.9 14.0 10.1 2028.5003 JUL 76.5 42.9 12.5 19.2 13.9 10.1 2028.5837 AUG 73.5 41.3 12.3 18.4 13.7 9.9 2028.6670 SEP 69.0 39.3 11.9 18.5 13.5 9.7 2028.7503 OCT 65.2 37.0 10.9 18.7 13.3 9.4 2028.8337 NOV 61.4 35.4 10.7 18.4 13.1 8.8 2028.9170 DEC 59.8 34.0 10.1 18.0 12.9 8.3 2029.0003 JAN 57.2 32.3 9.1 17.5 12.8 7.8 2029.0837 FEB 56.0 30.6 8.6 16.8 12.8 7.3 2029.1670 MAR 54.6 29.0 7.7 15.9 12.7 6.6 2029.2503 APR 53.7 27.6 6.4 15.9 12.5 6.2 2029.3337 MAY 52.3 25.9 5.9 16.0 12.4 6.3 2029.4170 JUN 50.4 24.4 5.8 16.1 12.4 6.5 2029.5003 JUL 48.3 23.0 5.5 16.0 12.3 6.9 2029.5837 AUG 46.1 21.6 5.4 16.2 12.3 7.2 2029.6670 SEP 43.2 20.0 4.2 16.6 12.1 7.2 2029.7503 OCT 40.0 18.5 3.2 16.5 11.9 7.2 2029.8337 NOV 35.5 17.2 2.7 16.1 11.6 7.1 2029.9170 DEC 30.0 15.6 2.5 15.8 11.4 7.1 2030.0003 JAN 26.3 13.8 2.1 14.8 10.9 7.0 2030.0837 FEB 24.5 11.9 1.4 13.3 10.5 7.0 2030.1670 MAR 23.4 10.3 1.1 12.3 10.1 6.9 2030.2503 APR 23.0 9.1 0.9 12.4 9.7 6.8 2030.3337 MAY 22.3 8.0 0.9 12.1 9.3 6.8 2030.4170 JUN 21.6 7.0 0.6 11.7 9.0 6.5 2030.5003 JUL 19.3 6.1 0.4 11.4 8.6 6.0 2030.5837 AUG 16.7 5.3 0.3 11.1 8.4 5.7 2030.6670 SEP 14.8 4.5 0.1 10.4 8.3 6.0 2030.7503 OCT 13.1 3.7 0.0 9.9 8.1 5.8