TABLE 4 ESTIMATES OF 13-MONTH SMOOTH SOLAR ACTIVITY FOR BALANCE OF CYCLE 24 CYCLE 25 AND BEGINNING OF CYCLE 26 TIME SUNSPOT NUMBERS GEOMAGNETIC INDEX (Ap) PERCENTILE PERCENTILE 95.0% 50% 5.0% 95.0% 50% 5.0% 2015.5837 AUG 72.5 67.4 62.8 13.8 12.4 11.6 2015.6670 SEP 75.7 65.6 57.8 15.4 12.6 11.2 2015.7503 OCT 78.1 63.3 53.0 16.8 13.0 10.5 2015.8337 NOV 79.8 61.3 49.3 17.6 13.5 10.1 2015.9170 DEC 80.9 59.1 46.0 18.2 14.2 10.4 2016.0003 JAN 81.0 57.0 42.0 19.8 15.1 11.1 2016.0837 FEB 82.2 55.8 39.2 20.8 15.7 11.7 2016.1670 MAR 84.0 54.0 34.8 21.9 16.2 12.3 2016.2503 APR 83.3 51.8 30.3 22.6 16.2 12.5 2016.3337 MAY 81.7 50.2 26.0 22.8 15.8 12.0 2016.4170 JUN 83.9 49.3 23.4 23.5 15.6 11.3 2016.5003 JUL 83.1 47.9 22.1 24.2 15.4 10.5 2016.5837 AUG 82.6 45.9 21.0 24.7 15.2 10.5 2016.6670 SEP 80.3 44.0 18.2 25.0 15.1 10.4 2016.7503 OCT 75.6 41.8 16.7 24.8 14.8 10.0 2016.8337 NOV 71.1 39.5 15.7 23.9 14.2 9.3 2016.9170 DEC 67.9 37.1 15.0 22.7 13.6 9.0 2017.0003 JAN 68.6 35.3 13.6 21.5 13.2 8.8 2017.0837 FEB 69.8 34.4 11.4 20.3 13.0 8.7 2017.1670 MAR 68.2 33.3 10.0 19.8 13.1 8.6 2017.2503 APR 65.3 31.9 10.3 19.7 13.4 8.9 2017.3337 MAY 61.2 30.4 11.4 20.1 14.1 9.6 2017.4170 JUN 58.3 29.0 11.7 20.5 14.7 10.7 2017.5003 JUL 57.3 27.8 10.6 20.8 15.2 11.5 2017.5837 AUG 55.5 26.7 9.1 20.5 15.3 12.0 2017.6670 SEP 52.3 25.4 6.3 20.0 15.4 12.2 2017.7503 OCT 49.9 24.2 3.6 20.1 15.5 12.4 2017.8337 NOV 49.6 24.1 1.6 19.8 15.6 12.4 2017.9170 DEC 49.4 23.8 -1.4 19.4 15.8 12.4 2018.0003 JAN 47.2 23.0 -4.3 19.4 16.1 12.2 2018.0837 FEB 43.5 22.2 -5.8 20.0 16.2 11.6 2018.1670 MAR 41.2 21.3 -6.5 20.0 16.1 10.8 2018.2503 APR 41.1 20.2 -7.2 19.8 15.9 10.5 2018.3337 MAY 39.4 19.4 -6.7 19.1 15.4 10.2 2018.4170 JUN 37.7 18.6 -6.2 18.3 15.0 10.1 2018.5003 JUL 36.0 17.8 -5.6 18.4 14.9 10.0 2018.5837 AUG 34.4 17.0 -5.1 18.7 14.9 9.9 2018.6670 SEP 32.8 16.3 -4.6 19.0 14.8 9.8 2018.7503 OCT 31.2 15.6 -4.1 18.9 14.5 9.7 2018.8337 NOV 29.7 14.9 -3.6 18.5 14.1 9.7 2018.9170 DEC 28.2 14.2 -3.1 17.7 13.5 9.4 2019.0003 JAN 26.8 13.5 -2.7 16.8 13.0 9.1 2019.0837 FEB 25.5 12.9 -2.2 16.0 12.4 8.8 2019.1670 MAR 24.3 12.3 -1.9 15.2 11.8 8.5 2019.2503 APR 23.2 11.8 -1.5 14.4 11.3 8.2 2019.3337 MAY 22.1 11.3 -1.2 13.7 10.8 7.9 2019.4170 JUN 21.2 10.9 -0.9 13.1 10.4 7.7 2019.5003 JUL 20.4 10.5 -0.6 12.5 10.0 7.5 2019.5837 AUG 19.7 10.2 -0.4 12.0 9.6 7.3 2019.6670 SEP 19.2 9.9 -0.2 11.6 9.3 7.1 2019.7503 OCT 18.8 9.8 -0.1 11.3 9.1 7.0 2019.8337 NOV 18.5 9.6 0.0 11.1 9.0 7.0 2019.9170 DEC 18.4 9.6 0.0 11.1 9.0 6.9 2020.0003 JAN 19.4 10.3 0.7 11.3 9.0 6.9 2020.0837 FEB 21.3 11.4 1.5 11.6 9.2 7.1 2020.1670 MAR 23.0 12.4 2.1 11.7 9.3 7.4 2020.2503 APR 25.6 13.4 2.8 11.9 9.4 7.5 2020.3337 MAY 28.5 14.7 3.2 12.0 9.5 7.5 2020.4170 JUN 33.4 16.2 3.9 12.1 9.6 7.3 2020.5003 JUL 37.0 17.8 5.0 12.2 9.7 7.2 2020.5837 AUG 40.7 19.5 5.4 12.5 9.9 7.1 2020.6670 SEP 46.2 21.6 5.5 12.8 10.1 7.0 2020.7503 OCT 53.3 23.9 5.8 13.2 10.5 7.2 2020.8337 NOV 63.8 26.8 5.8 13.7 10.8 7.6 2020.9170 DEC 72.8 30.1 5.9 14.5 11.1 7.9 2021.0003 JAN 79.8 33.3 7.0 15.7 11.4 7.7 2021.0837 FEB 90.0 37.0 7.1 16.1 11.6 7.7 2021.1670 MAR 101.3 41.0 7.1 16.3 11.8 7.6 2021.2503 APR 111.5 45.0 7.9 16.8 12.0 7.6 2021.3337 MAY 123.8 49.3 8.1 18.0 12.3 7.6 2021.4170 JUN 138.5 54.4 8.6 18.9 12.6 7.7 2021.5003 JUL 148.6 59.6 9.7 19.1 12.7 7.7 2021.5837 AUG 155.6 65.1 11.4 19.2 12.9 7.8 2021.6670 SEP 162.7 70.7 12.9 19.0 13.1 7.7 2021.7503 OCT 170.5 76.0 15.2 18.6 13.1 7.7 2021.8337 NOV 179.3 81.2 16.4 18.5 13.2 7.8 2021.9170 DEC 188.6 86.5 16.5 18.9 13.4 8.0 2022.0003 JAN 197.4 92.3 18.8 18.8 13.5 8.2 2022.0837 FEB 205.1 98.1 20.6 17.8 13.5 8.6 2022.1670 MAR 213.1 103.9 22.3 17.9 13.7 8.7 2022.2503 APR 217.8 109.7 24.3 18.5 13.9 8.7 2022.3337 MAY 224.3 115.1 25.1 19.1 14.2 9.0 2022.4170 JUN 225.7 119.9 26.1 19.6 14.6 9.4 2022.5003 JUL 226.2 124.5 27.1 20.3 14.9 9.6 2022.5837 AUG 231.6 128.4 27.8 20.3 15.1 9.6 2022.6670 SEP 234.1 131.7 28.6 20.3 15.1 9.8 2022.7503 OCT 236.5 135.4 28.5 20.5 15.2 10.0 2022.8337 NOV 239.8 139.1 27.9 20.8 15.4 10.5 2022.9170 DEC 242.1 142.9 27.3 21.2 15.4 11.1 2023.0003 JAN 248.6 146.3 28.1 21.3 15.3 11.6 2023.0837 FEB 256.1 149.3 29.0 21.4 15.1 11.3 2023.1670 MAR 261.0 152.2 31.1 21.6 15.0 11.2 2023.2503 APR 265.2 155.6 34.4 22.0 15.0 10.7 2023.3337 MAY 269.9 158.3 36.3 22.8 14.9 10.2 2023.4170 JUN 273.3 160.2 38.5 22.5 14.7 9.9 2023.5003 JUL 275.4 161.5 42.4 21.3 14.5 10.1 2023.5837 AUG 276.6 161.7 46.7 20.6 14.3 10.1 2023.6670 SEP 278.0 162.3 51.3 20.1 14.2 10.3 2023.7503 OCT 277.7 163.6 53.5 19.6 14.1 10.6 2023.8337 NOV 276.5 164.4 55.6 19.5 14.0 10.6 2023.9170 DEC 277.8 165.0 59.6 19.3 14.0 10.5 2024.0003 JAN 277.3 163.6 62.2 19.1 14.2 10.5 2024.0837 FEB 271.7 161.4 66.0 18.9 14.6 10.5 2024.1670 MAR 265.1 160.1 68.7 18.9 14.7 10.3 2024.2503 APR 259.1 159.5 71.3 19.5 14.6 9.8 2024.3337 MAY 255.5 159.4 73.2 20.4 14.7 10.2 2024.4170 JUN 253.8 159.1 73.0 22.0 15.0 10.7 2024.5003 JUL 252.1 158.6 72.1 23.4 15.3 10.7 2024.5837 AUG 250.8 157.9 73.3 24.0 15.4 10.9 2024.6670 SEP 248.8 156.9 76.5 25.1 15.7 11.1 2024.7503 OCT 247.1 156.2 76.7 25.6 15.9 11.3 2024.8337 NOV 245.1 155.2 75.1 24.9 15.9 11.5 2024.9170 DEC 244.0 154.0 74.0 24.8 15.9 11.7 2025.0003 JAN 241.6 152.7 74.9 23.9 15.8 11.9 2025.0837 FEB 237.3 150.3 75.8 22.1 15.8 11.8 2025.1670 MAR 232.2 147.1 73.7 22.4 15.9 12.0 2025.2503 APR 227.9 144.2 72.9 23.1 16.0 11.8 2025.3337 MAY 223.3 142.1 74.5 23.1 16.0 11.1 2025.4170 JUN 217.2 140.1 76.2 22.6 16.0 10.8 2025.5003 JUL 212.3 137.3 74.2 22.0 15.8 10.8 2025.5837 AUG 206.6 134.3 70.9 21.9 15.8 10.8 2025.6670 SEP 202.1 132.0 69.3 22.7 16.1 10.8 2025.7503 OCT 200.6 130.4 68.8 23.7 16.5 10.8 2025.8337 NOV 195.3 128.0 65.5 23.9 16.7 10.8 2025.9170 DEC 192.5 125.1 58.4 23.9 17.0 10.7 2026.0003 JAN 190.7 122.2 56.8 23.9 17.1 10.6 2026.0837 FEB 185.9 119.5 58.9 23.5 17.2 10.3 2026.1670 MAR 180.3 117.3 57.6 22.5 17.2 10.5 2026.2503 APR 174.5 115.4 54.5 22.7 17.2 10.7 2026.3337 MAY 168.9 113.7 52.9 23.0 17.4 11.4 2026.4170 JUN 164.2 111.5 51.5 23.1 17.6 11.9 2026.5003 JUL 161.0 108.9 49.0 22.5 17.8 12.0 2026.5837 AUG 155.7 105.8 46.2 21.7 17.6 12.1 2026.6670 SEP 146.7 102.3 44.6 21.2 17.4 12.3 2026.7503 OCT 138.4 98.5 44.0 21.7 17.0 12.5 2026.8337 NOV 137.2 95.4 44.4 21.7 16.9 13.3 2026.9170 DEC 135.8 92.7 42.9 22.1 16.9 13.1 2027.0003 JAN 131.4 90.2 40.5 22.6 17.0 12.8 2027.0837 FEB 126.9 87.8 40.8 22.3 16.8 13.1 2027.1670 MAR 122.3 85.2 39.7 22.4 16.5 12.7 2027.2503 APR 116.8 82.5 37.9 22.7 16.2 12.5 2027.3337 MAY 115.9 80.0 36.5 22.9 15.8 12.1 2027.4170 JUN 116.9 77.4 34.0 23.5 15.6 11.2 2027.5003 JUL 115.4 74.6 31.6 24.1 15.4 10.5 2027.5837 AUG 114.0 71.8 27.9 24.8 15.3 10.7 2027.6670 SEP 111.6 69.9 24.8 25.3 15.3 10.8 2027.7503 OCT 107.6 67.9 22.9 25.6 15.3 10.6 2027.8337 NOV 103.7 65.9 19.9 25.4 15.3 10.8 2027.9170 DEC 100.5 63.7 17.4 24.9 15.2 11.0 2028.0003 JAN 99.6 61.4 15.8 24.0 15.0 11.1 2028.0837 FEB 98.6 59.2 14.5 23.0 14.9 11.3 2028.1670 MAR 95.5 57.1 13.2 22.5 15.0 11.2 2028.2503 APR 91.7 55.0 13.1 22.1 15.1 11.1 2028.3337 MAY 86.5 52.6 13.2 21.8 15.2 11.2 2028.4170 JUN 84.9 50.8 12.6 21.4 15.3 11.4 2028.5003 JUL 85.1 49.4 12.5 20.7 15.2 11.5 2028.5837 AUG 82.2 47.8 12.3 19.9 14.9 11.3 2028.6670 SEP 77.6 45.8 11.9 20.0 14.7 11.1 2028.7503 OCT 73.9 43.5 10.9 20.1 14.6 10.8 2028.8337 NOV 70.0 41.9 10.7 19.9 14.3 10.1 2028.9170 DEC 68.4 40.5 10.1 19.5 14.2 9.6 2029.0003 JAN 65.9 38.8 9.1 19.0 14.1 9.1 2029.0837 FEB 64.6 37.1 8.6 18.3 14.1 8.6 2029.1670 MAR 63.3 35.5 7.7 17.3 14.0 8.0 2029.2503 APR 62.3 34.1 6.5 17.4 13.8 7.5 2029.3337 MAY 60.9 32.4 5.9 17.5 13.7 7.6 2029.4170 JUN 59.1 30.9 5.9 17.6 13.7 7.8 2029.5003 JUL 57.0 29.5 5.5 17.5 13.6 8.3 2029.5837 AUG 54.8 28.1 5.4 17.7 13.5 8.6 2029.6670 SEP 51.8 26.5 4.3 18.1 13.4 8.5 2029.7503 OCT 48.6 25.0 3.2 17.9 13.2 8.6 2029.8337 NOV 44.1 23.7 2.7 17.6 12.9 8.5 2029.9170 DEC 38.6 22.1 2.5 17.3 12.6 8.5 2030.0003 JAN 34.9 20.3 2.1 16.3 12.2 8.4 2030.0837 FEB 33.1 18.4 1.5 14.8 11.8 8.4 2030.1670 MAR 32.1 16.8 1.1 13.8 11.4 8.3 2030.2503 APR 31.6 15.6 0.9 13.9 11.0 8.2 2030.3337 MAY 31.0 14.5 0.9 13.6 10.6 8.2 2030.4170 JUN 30.2 13.5 0.6 13.2 10.3 7.9 2030.5003 JUL 27.9 12.6 0.5 12.9 9.9 7.4 2030.5837 AUG 25.3 11.8 0.3 12.6 9.7 7.1 2030.6670 SEP 23.4 11.0 0.1 11.9 9.5 7.3 2030.7503 OCT 21.8 10.2 0.0 11.4 9.4 7.1