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% 2018.5837 AUG 9.7 6.4 5.0 7.2 6.8 6.3 2018.6670 SEP 11.4 6.0 1.6 7.7 6.8 6.0 2018.7503 OCT 12.1 5.9 0.0 8.5 7.0 5.3 2018.8337 NOV 13.0 6.2 0.0 9.2 7.2 5.2 2018.9170 DEC 13.4 6.2 0.0 9.4 7.3 5.2 2019.0003 JAN 13.6 5.9 0.0 9.4 7.5 5.2 2019.0837 FEB 13.8 5.4 0.0 9.5 7.8 5.5 2019.1670 MAR 14.5 5.0 0.0 10.4 8.2 6.0 2019.2503 APR 15.6 4.9 0.0 11.2 8.5 6.2 2019.3337 MAY 16.3 4.8 0.0 11.4 8.6 6.3 2019.4170 JUN 16.6 4.7 0.0 11.2 8.4 6.1 2019.5003 JUL 16.0 4.6 0.0 10.8 8.0 5.8 2019.5837 AUG 14.2 4.3 0.0 10.4 7.7 5.5 2019.6670 SEP 11.8 3.9 0.0 9.8 7.7 5.6 2019.7503 OCT 10.8 3.5 0.0 9.5 7.7 5.6 2019.8337 NOV 10.0 3.1 0.0 9.4 7.6 5.4 2019.9170 DEC 10.0 3.1 0.0 9.4 7.6 5.4 2020.0003 JAN 11.0 3.8 0.7 9.6 7.7 5.4 2020.0837 FEB 12.8 4.9 1.4 9.9 7.9 5.6 2020.1670 MAR 14.5 6.0 2.0 10.0 8.0 5.9 2020.2503 APR 17.1 7.0 2.8 10.2 8.1 6.0 2020.3337 MAY 20.1 8.2 3.2 10.3 8.2 6.0 2020.4170 JUN 24.9 9.7 3.9 10.4 8.2 5.8 2020.5003 JUL 28.5 11.3 5.0 10.6 8.3 5.7 2020.5837 AUG 32.2 13.1 5.4 10.9 8.5 5.6 2020.6670 SEP 37.7 15.1 5.5 11.2 8.8 5.5 2020.7503 OCT 44.8 17.4 5.8 11.6 9.2 5.7 2020.8337 NOV 55.4 20.4 5.7 12.1 9.5 6.1 2020.9170 DEC 64.4 23.6 5.9 12.9 9.8 6.3 2021.0003 JAN 71.4 26.8 7.0 14.1 10.1 6.2 2021.0837 FEB 81.6 30.5 7.1 14.5 10.3 6.2 2021.1670 MAR 92.8 34.5 7.1 14.7 10.4 6.1 2021.2503 APR 103.0 38.5 7.9 15.2 10.6 6.0 2021.3337 MAY 115.4 42.8 8.0 16.4 10.9 6.1 2021.4170 JUN 130.0 48.0 8.6 17.3 11.2 6.2 2021.5003 JUL 140.1 53.2 9.7 17.5 11.4 6.2 2021.5837 AUG 147.1 58.6 11.4 17.6 11.6 6.3 2021.6670 SEP 154.2 64.2 12.9 17.4 11.7 6.2 2021.7503 OCT 162.0 69.5 15.1 17.0 11.8 6.2 2021.8337 NOV 170.8 74.7 16.4 16.9 11.9 6.3 2021.9170 DEC 180.1 80.1 16.5 17.3 12.1 6.5 2022.0003 JAN 189.0 85.8 18.7 17.2 12.1 6.7 2022.0837 FEB 196.6 91.6 20.6 16.2 12.2 7.0 2022.1670 MAR 204.6 97.5 22.3 16.3 12.4 7.1 2022.2503 APR 209.3 103.2 24.2 16.8 12.6 7.2 2022.3337 MAY 215.8 108.6 25.1 17.4 12.8 7.5 2022.4170 JUN 217.3 113.4 26.1 17.9 13.3 7.9 2022.5003 JUL 217.7 118.0 27.1 18.7 13.6 8.1 2022.5837 AUG 223.1 121.9 27.8 18.7 13.7 8.1 2022.6670 SEP 225.6 125.2 28.5 18.7 13.8 8.3 2022.7503 OCT 228.0 128.9 28.5 18.9 13.9 8.5 2022.8337 NOV 231.3 132.6 27.9 19.2 14.0 9.0 2022.9170 DEC 233.7 136.4 27.3 19.5 14.1 9.6 2023.0003 JAN 240.1 139.8 28.0 19.6 13.9 10.1 2023.0837 FEB 247.7 142.8 29.0 19.7 13.7 9.8 2023.1670 MAR 252.5 145.7 31.1 20.0 13.7 9.7 2023.2503 APR 256.8 149.1 34.3 20.4 13.7 9.2 2023.3337 MAY 261.4 151.8 36.2 21.1 13.6 8.7 2023.4170 JUN 264.8 153.7 38.5 20.8 13.4 8.4 2023.5003 JUL 266.9 155.0 42.4 19.7 13.1 8.6 2023.5837 AUG 268.1 155.2 46.7 19.0 13.0 8.6 2023.6670 SEP 269.5 155.9 51.3 18.4 12.9 8.8 2023.7503 OCT 269.2 157.1 53.5 18.0 12.7 9.1 2023.8337 NOV 268.1 158.0 55.6 17.9 12.7 9.1 2023.9170 DEC 269.3 158.5 59.5 17.7 12.7 9.0 2024.0003 JAN 268.8 157.1 62.2 17.5 12.9 9.0 2024.0837 FEB 263.2 154.9 66.0 17.3 13.2 9.0 2024.1670 MAR 256.6 153.6 68.7 17.3 13.3 8.8 2024.2503 APR 250.6 153.0 71.3 17.8 13.2 8.3 2024.3337 MAY 247.0 152.9 73.2 18.7 13.4 8.7 2024.4170 JUN 245.3 152.6 72.9 20.4 13.7 9.2 2024.5003 JUL 243.6 152.1 72.1 21.7 13.9 9.2 2024.5837 AUG 242.4 151.4 73.3 22.4 14.1 9.4 2024.6670 SEP 240.3 150.4 76.5 23.5 14.3 9.6 2024.7503 OCT 238.7 149.7 76.7 24.0 14.5 9.8 2024.8337 NOV 236.6 148.7 75.1 23.3 14.6 10.0 2024.9170 DEC 235.5 147.5 74.0 23.2 14.5 10.2 2025.0003 JAN 233.1 146.2 74.9 22.3 14.5 10.3 2025.0837 FEB 228.8 143.8 75.7 20.5 14.5 10.3 2025.1670 MAR 223.7 140.6 73.7 20.8 14.5 10.5 2025.2503 APR 219.5 137.7 72.9 21.5 14.6 10.3 2025.3337 MAY 214.8 135.7 74.5 21.5 14.7 9.5 2025.4170 JUN 208.7 133.6 76.2 21.0 14.6 9.3 2025.5003 JUL 203.8 130.8 74.2 20.4 14.5 9.3 2025.5837 AUG 198.1 127.8 70.9 20.3 14.5 9.3 2025.6670 SEP 193.6 125.5 69.3 21.1 14.8 9.2 2025.7503 OCT 192.1 123.9 68.8 22.0 15.1 9.3 2025.8337 NOV 186.8 121.5 65.5 22.3 15.4 9.3 2025.9170 DEC 184.0 118.6 58.3 22.3 15.6 9.2 2026.0003 JAN 182.2 115.7 56.8 22.3 15.8 9.1 2026.0837 FEB 177.4 113.1 58.9 21.9 15.8 8.8 2026.1670 MAR 171.8 110.9 57.6 20.9 15.9 8.9 2026.2503 APR 166.0 109.0 54.5 21.1 15.9 9.1 2026.3337 MAY 160.5 107.2 52.9 21.4 16.0 9.9 2026.4170 JUN 155.8 105.0 51.5 21.5 16.3 10.4 2026.5003 JUL 152.5 102.4 49.0 20.9 16.4 10.5 2026.5837 AUG 147.3 99.3 46.2 20.0 16.3 10.6 2026.6670 SEP 138.2 95.8 44.6 19.6 16.0 10.8 2026.7503 OCT 129.9 92.0 44.0 20.1 15.7 10.9 2026.8337 NOV 128.7 88.9 44.4 20.1 15.5 11.8 2026.9170 DEC 127.3 86.2 42.9 20.5 15.6 11.6 2027.0003 JAN 122.9 83.7 40.5 20.9 15.6 11.3 2027.0837 FEB 118.4 81.3 40.7 20.7 15.4 11.5 2027.1670 MAR 113.8 78.7 39.7 20.7 15.2 11.2 2027.2503 APR 108.3 76.0 37.9 21.0 14.9 11.0 2027.3337 MAY 107.5 73.5 36.4 21.3 14.5 10.6 2027.4170 JUN 108.5 71.0 34.0 21.8 14.3 9.7 2027.5003 JUL 107.0 68.1 31.6 22.5 14.0 9.0 2027.5837 AUG 105.5 65.4 27.8 23.2 13.9 9.2 2027.6670 SEP 103.1 63.4 24.8 23.7 14.0 9.3 2027.7503 OCT 99.2 61.5 22.9 23.9 14.0 9.1 2027.8337 NOV 95.3 59.5 19.9 23.8 13.9 9.2 2027.9170 DEC 92.0 57.2 17.3 23.3 13.8 9.5 2028.0003 JAN 91.1 54.9 15.8 22.3 13.6 9.6 2028.0837 FEB 90.1 52.8 14.5 21.4 13.6 9.8 2028.1670 MAR 87.1 50.7 13.2 20.9 13.7 9.7 2028.2503 APR 83.2 48.5 13.0 20.5 13.8 9.6 2028.3337 MAY 78.0 46.1 13.2 20.2 13.9 9.7 2028.4170 JUN 76.4 44.3 12.6 19.7 14.0 9.9 2028.5003 JUL 76.6 42.9 12.5 19.1 13.8 9.9 2028.5837 AUG 73.7 41.3 12.3 18.3 13.6 9.8 2028.6670 SEP 69.2 39.3 11.9 18.4 13.4 9.6 2028.7503 OCT 65.4 37.1 10.9 18.5 13.2 9.2 2028.8337 NOV 61.5 35.4 10.7 18.2 13.0 8.6 2028.9170 DEC 60.0 34.0 10.1 17.8 12.8 8.1 2029.0003 JAN 57.4 32.3 9.1 17.3 12.8 7.6 2029.0837 FEB 56.1 30.6 8.6 16.6 12.8 7.1 2029.1670 MAR 54.8 29.1 7.7 15.7 12.6 6.4 2029.2503 APR 53.9 27.6 6.4 15.7 12.5 6.0 2029.3337 MAY 52.4 25.9 5.9 15.8 12.4 6.1 2029.4170 JUN 50.6 24.4 5.8 15.9 12.3 6.3 2029.5003 JUL 48.5 23.0 5.5 15.9 12.2 6.7 2029.5837 AUG 46.3 21.6 5.4 16.1 12.2 7.1 2029.6670 SEP 43.3 20.0 4.2 16.4 12.1 7.0 2029.7503 OCT 40.2 18.5 3.2 16.3 11.8 7.0 2029.8337 NOV 35.6 17.2 2.7 16.0 11.6 7.0 2029.9170 DEC 30.1 15.6 2.5 15.7 11.3 7.0 2030.0003 JAN 26.4 13.8 2.1 14.7 10.9 6.9 2030.0837 FEB 24.6 11.9 1.4 13.2 10.4 6.9 2030.1670 MAR 23.6 10.4 1.1 12.2 10.0 6.8 2030.2503 APR 23.1 9.1 0.9 12.3 9.7 6.7 2030.3337 MAY 22.5 8.0 0.9 12.0 9.3 6.7 2030.4170 JUN 21.7 7.0 0.6 11.6 8.9 6.4 2030.5003 JUL 19.5 6.2 0.4 11.3 8.6 5.9 2030.5837 AUG 16.8 5.3 0.3 11.0 8.4 5.6 2030.6670 SEP 14.9 4.5 0.1 10.2 8.2 5.8 2030.7503 OCT 13.3 3.7 0.0 9.7 8.0 5.6