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% 2015.2503 APR 88.2 81.4 78.0 11.9 11.1 9.8 2015.3337 MAY 91.9 80.4 74.4 13.1 11.5 9.6 2015.4170 JUN 93.8 79.1 72.7 14.5 12.0 10.0 2015.5003 JUL 92.5 77.7 70.0 15.8 12.6 10.5 2015.5837 AUG 94.2 76.2 65.9 17.4 13.2 11.2 2015.6670 SEP 96.0 74.3 61.9 18.9 13.8 11.5 2015.7503 OCT 97.1 71.9 58.2 20.1 14.4 11.5 2015.8337 NOV 97.1 69.9 54.8 20.7 15.1 11.6 2015.9170 DEC 93.7 67.6 51.2 20.9 15.9 12.0 2016.0003 JAN 90.2 65.3 47.1 22.3 16.7 12.6 2016.0837 FEB 90.4 63.8 44.1 22.8 17.2 13.4 2016.1670 MAR 93.0 61.9 38.6 23.4 17.4 14.2 2016.2503 APR 95.1 59.8 34.3 23.8 17.2 14.2 2016.3337 MAY 97.0 58.0 30.8 23.7 16.5 13.3 2016.4170 JUN 99.0 56.7 28.0 24.3 16.4 12.5 2016.5003 JUL 98.5 55.0 26.6 25.0 16.2 11.8 2016.5837 AUG 97.6 52.9 23.8 25.4 15.8 11.5 2016.6670 SEP 95.2 50.9 21.2 25.7 15.6 11.3 2016.7503 OCT 91.0 48.7 19.5 25.7 15.4 10.8 2016.8337 NOV 86.6 46.4 18.3 25.0 14.9 10.1 2016.9170 DEC 83.4 44.0 17.6 24.1 14.5 9.8 2017.0003 JAN 83.0 42.1 16.4 23.0 14.2 9.7 2017.0837 FEB 83.7 41.0 15.1 22.0 14.0 9.7 2017.1670 MAR 81.4 39.6 13.8 21.7 14.3 10.0 2017.2503 APR 78.0 37.9 14.0 21.9 14.9 10.7 2017.3337 MAY 73.3 36.1 14.8 22.3 15.7 12.0 2017.4170 JUN 68.4 34.6 15.0 22.6 16.4 12.6 2017.5003 JUL 66.1 33.3 13.9 22.5 16.7 13.3 2017.5837 AUG 65.0 32.0 12.5 22.1 16.8 13.5 2017.6670 SEP 62.0 30.6 10.8 21.1 16.7 13.8 2017.7503 OCT 59.1 29.2 9.1 20.6 16.6 14.0 2017.8337 NOV 58.8 28.9 6.3 20.5 16.5 13.7 2017.9170 DEC 58.9 28.5 3.4 20.3 16.5 13.5 2018.0003 JAN 56.3 27.6 0.6 20.0 16.8 13.4 2018.0837 FEB 52.1 26.6 -1.0 20.2 16.8 12.8 2018.1670 MAR 48.0 25.4 -2.0 20.1 16.6 11.9 2018.2503 APR 46.4 24.2 -3.0 19.6 16.2 11.4 2018.3337 MAY 44.3 23.1 -2.8 18.9 15.6 10.7 2018.4170 JUN 42.3 22.0 -2.6 18.4 15.2 10.3 2018.5003 JUL 40.2 20.9 -2.3 18.6 15.1 10.6 2018.5837 AUG 38.2 19.9 -2.1 17.9 14.6 10.3 2018.6670 SEP 36.2 18.8 -1.9 17.3 14.0 10.0 2018.7503 OCT 34.2 17.8 -1.7 16.6 13.5 9.7 2018.8337 NOV 32.3 16.8 -1.5 16.0 13.0 9.4 2018.9170 DEC 30.5 15.9 -1.3 15.4 12.5 9.1 2019.0003 JAN 28.8 15.0 -1.1 14.8 12.0 8.8 2019.0837 FEB 27.2 14.2 -0.9 14.2 11.5 8.5 2019.1670 MAR 25.7 13.4 -0.8 13.7 11.1 8.2 2019.2503 APR 24.3 12.6 -0.6 13.2 10.7 8.0 2019.3337 MAY 23.0 12.0 -0.5 12.7 10.3 7.8 2019.4170 JUN 21.8 11.4 -0.3 12.3 10.0 7.6 2019.5003 JUL 20.8 10.9 -0.2 11.9 9.7 7.4 2019.5837 AUG 20.0 10.4 -0.1 11.6 9.4 7.2 2019.6670 SEP 19.3 10.1 -0.1 11.4 9.2 7.1 2019.7503 OCT 18.8 9.8 0.0 11.2 9.1 7.0 2019.8337 NOV 18.5 9.7 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