TABLE 4 ESTIMATES OF 13-MONTH SMOOTH SOLAR ACTIVITY FOR BALANCE OF CYCLE 25 WITH A MEAN CYCLE GIVEN FOR CYCLE 26 TIME SUNSPOT NUMBERS GEOMAGNETIC INDEX (Ap) PERCENTILE PERCENTILE 95.0% 50% 5.0% 95.0% 50% 5.0% 2020.5837 AUG 13.2 9.9 7.7 5.7 5.2 5.0 2020.6670 SEP 18.1 10.9 7.4 5.8 5.2 4.8 2020.7503 OCT 21.6 11.9 6.5 6.4 5.4 4.9 2020.8337 NOV 24.3 12.9 5.3 7.2 5.7 4.8 2020.9170 DEC 27.8 14.4 4.6 7.7 5.8 4.6 2021.0003 JAN 31.5 16.1 3.8 7.8 5.8 4.2 2021.0837 FEB 35.3 17.8 2.1 8.4 5.9 4.0 2021.1670 MAR 41.3 19.9 0.0 9.0 5.9 3.7 2021.2503 APR 47.6 22.6 0.0 9.8 6.0 3.2 2021.3337 MAY 56.3 25.1 0.0 10.9 6.2 3.1 2021.4170 JUN 66.5 27.6 0.7 11.9 6.5 3.2 2021.5003 JUL 76.4 31.1 2.9 12.1 6.7 3.2 2021.5837 AUG 85.9 35.6 4.4 12.1 6.9 3.2 2021.6670 SEP 94.9 40.3 5.3 11.5 6.9 3.2 2021.7503 OCT 104.0 45.2 8.4 10.9 6.7 3.3 2021.8337 NOV 114.9 49.7 12.2 10.3 6.6 3.5 2021.9170 DEC 126.6 53.9 14.2 9.9 6.7 3.5 2022.0003 JAN 137.1 58.8 15.5 9.9 6.8 3.8 2022.0837 FEB 146.2 63.4 16.5 9.9 7.1 4.7 2022.1670 MAR 157.2 67.5 17.3 10.2 7.5 5.3 2022.2503 APR 168.5 72.2 19.2 10.1 7.8 5.6 2022.3337 MAY 175.4 76.7 21.2 10.1 8.0 5.7 2022.4170 JUN 179.2 81.5 24.7 10.7 8.2 5.2 2022.5003 JUL 185.1 85.7 26.8 11.5 8.5 4.9 2022.5837 AUG 190.8 88.4 25.9 11.7 8.6 4.8 2022.6670 SEP 196.5 91.0 25.9 12.2 9.0 5.0 2022.7503 OCT 205.0 94.1 28.6 13.1 9.5 5.3 2022.8337 NOV 212.4 97.6 31.5 13.9 9.7 5.0 2022.9170 DEC 217.5 101.8 34.2 14.3 9.8 4.7 2023.0003 JAN 224.8 106.4 39.2 14.8 10.2 4.5 2023.0837 FEB 232.7 110.3 43.8 15.4 10.4 4.2 2023.1670 MAR 237.7 113.3 46.0 15.7 10.5 4.2 2023.2503 APR 241.9 115.9 48.5 16.2 10.5 4.4 2023.3337 MAY 246.5 118.1 49.5 17.2 10.6 4.4 2023.4170 JUN 250.0 120.3 49.0 17.4 10.6 4.5 2023.5003 JUL 252.7 122.7 49.5 16.8 10.7 4.9 2023.5837 AUG 254.8 125.1 52.2 16.5 10.8 5.3 2023.6670 SEP 257.2 127.7 54.7 16.0 10.8 5.5 2023.7503 OCT 257.3 129.4 56.6 15.4 10.5 5.5 2023.8337 NOV 256.9 131.2 58.4 15.3 10.6 5.7 2023.9170 DEC 258.4 132.4 59.0 15.1 10.6 5.9 2024.0003 JAN 258.1 132.3 59.4 14.4 10.4 5.6 2024.0837 FEB 253.5 132.5 59.6 13.6 10.3 5.9 2024.1670 MAR 248.4 133.3 60.6 12.8 9.8 6.0 2024.2503 APR 243.8 134.8 63.7 12.4 9.3 5.8 2024.3337 MAY 240.6 135.8 66.3 12.5 9.1 5.6 2024.4170 JUN 239.0 136.1 67.1 13.5 9.1 5.3 2024.5003 JUL 237.6 136.5 67.1 14.4 9.1 5.2 2024.5837 AUG 236.3 137.6 68.9 14.9 9.2 5.4 2024.6670 SEP 234.9 138.2 71.8 15.6 9.2 5.3 2024.7503 OCT 234.1 138.2 71.3 15.7 9.2 5.2 2024.8337 NOV 232.0 137.5 69.7 15.3 9.4 5.6 2024.9170 DEC 231.9 136.9 68.8 15.0 9.3 5.5 2025.0003 JAN 230.2 136.7 70.2 14.0 9.1 5.8 2025.0837 FEB 226.2 135.5 71.4 13.5 9.1 5.8 2025.1670 MAR 222.2 133.1 71.9 13.5 9.4 6.6 2025.2503 APR 218.5 130.8 72.3 14.4 9.7 6.8 2025.3337 MAY 214.1 128.8 70.1 14.6 9.9 7.0 2025.4170 JUN 207.8 127.0 67.7 15.0 10.3 6.9 2025.5003 JUL 203.0 124.6 66.4 15.5 10.5 7.2 2025.5837 AUG 198.6 122.1 64.5 14.7 10.3 7.0 2025.6670 SEP 194.5 120.5 63.4 15.0 10.4 6.8 2025.7503 OCT 191.2 119.7 63.2 15.6 10.7 6.9 2025.8337 NOV 187.1 118.2 62.3 15.6 10.8 6.8 2025.9170 DEC 184.6 115.8 57.9 15.4 10.8 6.7 2026.0003 JAN 183.2 113.5 56.2 15.5 10.9 6.6 2026.0837 FEB 178.8 111.4 55.9 15.6 11.2 6.5 2026.1670 MAR 172.9 109.0 52.5 14.9 11.6 7.1 2026.2503 APR 166.5 106.5 48.8 14.9 12.0 7.6 2026.3337 MAY 160.7 104.1 46.9 15.6 12.3 8.4 2026.4170 JUN 155.9 101.7 45.5 16.0 12.6 8.3 2026.5003 JUL 152.7 99.3 43.4 15.9 12.9 8.7 2026.5837 AUG 148.2 97.1 41.3 16.3 13.1 9.2 2026.6670 SEP 139.9 94.4 40.3 17.6 13.1 9.3 2026.7503 OCT 132.0 91.2 39.5 18.3 13.0 9.4 2026.8337 NOV 130.6 87.8 39.3 18.6 13.3 9.7 2026.9170 DEC 128.3 84.2 37.2 18.8 13.5 9.8 2027.0003 JAN 123.6 81.2 35.5 19.2 13.6 9.9 2027.0837 FEB 118.3 79.0 35.7 18.9 13.5 9.3 2027.1670 MAR 114.2 76.8 34.8 19.0 13.4 9.1 2027.2503 APR 112.0 74.9 31.3 19.5 13.3 9.1 2027.3337 MAY 113.3 73.0 28.0 19.7 13.1 8.6 2027.4170 JUN 114.5 71.3 26.1 20.0 12.7 7.6 2027.5003 JUL 113.1 68.5 23.5 20.5 12.3 6.7 2027.5837 AUG 111.5 65.9 21.1 21.1 12.1 6.7 2027.6670 SEP 109.2 64.0 19.7 21.6 12.0 6.8 2027.7503 OCT 105.4 61.8 18.2 22.0 12.1 6.8 2027.8337 NOV 101.4 59.9 16.9 21.7 11.8 6.8 2027.9170 DEC 98.5 58.1 14.9 21.1 11.6 6.9 2028.0003 JAN 98.1 56.7 13.8 20.2 11.4 6.4 2028.0837 FEB 97.5 55.5 12.9 19.5 11.4 6.0 2028.1670 MAR 94.9 54.2 12.2 19.4 11.7 5.8 2028.2503 APR 91.3 52.7 12.7 19.0 11.8 5.1 2028.3337 MAY 86.3 50.6 13.0 18.9 12.1 4.7 2028.4170 JUN 83.8 48.7 12.3 18.7 12.3 4.7 2028.5003 JUL 84.7 47.8 12.6 18.2 12.4 5.3 2028.5837 AUG 82.4 46.7 12.7 18.4 12.3 5.7 2028.6670 SEP 77.2 44.1 11.8 18.6 12.2 6.1 2028.7503 OCT 73.0 41.3 10.8 18.7 12.0 6.0 2028.8337 NOV 69.1 39.2 10.4 18.5 12.0 6.2 2028.9170 DEC 68.0 37.2 9.7 18.3 12.1 6.5 2029.0003 JAN 64.7 34.8 8.7 18.1 12.5 7.0 2029.0837 FEB 59.9 32.6 7.8 17.5 12.7 7.3 2029.1670 MAR 56.0 30.7 6.6 16.7 12.7 7.3 2029.2503 APR 54.4 28.7 5.3 16.7 12.4 7.1 2029.3337 MAY 52.8 27.0 4.9 16.7 12.1 6.9 2029.4170 JUN 51.2 25.7 4.6 16.7 11.9 6.5 2029.5003 JUL 49.7 24.7 4.3 16.8 11.8 6.0 2029.5837 AUG 48.1 23.7 4.0 17.3 12.0 6.0 2029.6670 SEP 46.0 22.7 3.1 17.7 12.0 6.4 2029.7503 OCT 43.1 21.6 2.3 17.6 11.9 6.6 2029.8337 NOV 39.8 20.9 2.0 17.3 11.7 6.6 2029.9170 DEC 35.5 19.7 2.1 17.0 11.4 6.4 2030.0003 JAN 33.7 18.1 1.7 15.9 10.9 6.4 2030.0837 FEB 32.2 16.7 1.2 14.3 10.3 6.3 2030.1670 MAR 31.5 15.5 0.9 13.0 9.8 6.0 2030.2503 APR 31.3 14.7 0.9 13.1 9.4 5.8 2030.3337 MAY 30.7 13.6 0.9 12.8 9.0 5.7 2030.4170 JUN 29.6 12.4 0.6 12.4 8.8 5.6 2030.5003 JUL 27.2 11.4 0.4 12.3 8.7 5.5 2030.5837 AUG 24.5 10.6 0.2 12.0 8.5 5.2 2030.6670 SEP 22.5 9.9 0.0 11.3 8.3 4.7 2030.7503 OCT 20.9 9.2 0.0 10.8 8.1 4.2 2030.8337 NOV 18.5 8.7 0.0 10.6 7.9 3.9 2030.9170 DEC 18.5 8.7 0.0 10.6 7.9 4.0 2031.0003 JAN 19.4 9.4 0.7 10.9 8.1 3.8 2031.0837 FEB 21.2 10.6 1.3 11.2 8.3 3.9 2031.1670 MAR 23.0 11.7 1.7 11.4 8.4 3.8 2031.2503 APR 25.6 12.8 2.3 11.6 8.6 3.6 2031.3337 MAY 28.5 14.0 2.5 11.8 8.7 3.4 2031.4170 JUN 33.1 15.6 3.2 11.9 8.8 3.4 2031.5003 JUL 36.6 17.4 4.4 12.1 9.0 3.4 2031.5837 AUG 40.3 19.2 5.0 12.4 9.2 3.3 2031.6670 SEP 45.8 21.4 5.6 12.8 9.5 3.4 2031.7503 OCT 52.8 23.7 6.1 13.2 10.0 3.7 2031.8337 NOV 63.1 26.6 6.1 13.8 10.4 4.2 2031.9170 DEC 71.9 29.9 6.3 14.6 10.6 4.5 2032.0003 JAN 78.8 33.1 7.3 15.7 10.9 4.7 2032.0837 FEB 88.8 36.7 7.3 16.1 11.1 4.8 2032.1670 MAR 99.7 40.7 7.3 16.3 11.3 5.0 2032.2503 APR 109.4 44.7 8.0 16.9 11.4 5.1 2032.3337 MAY 121.3 49.1 8.2 18.0 11.6 5.3 2032.4170 JUN 135.7 53.9 8.9 18.9 11.9 5.4 2032.5003 JUL 145.7 58.8 10.0 19.1 12.1 5.6 2032.5837 AUG 152.6 64.1 11.7 19.2 12.3 5.8 2032.6670 SEP 159.7 69.6 13.3 19.0 12.6 6.0 2032.7503 OCT 167.7 74.9 15.6 18.6 12.7 6.1 2032.8337 NOV 176.7 80.0 16.9 18.5 12.7 6.1 2032.9170 DEC 186.4 85.3 17.0 18.9 12.8 6.1 2033.0003 JAN 195.5 91.2 19.1 18.8 12.9 6.3 2033.0837 FEB 203.4 97.0 20.9 17.8 13.0 6.5 2033.1670 MAR 211.7 102.6 22.7 17.9 13.2 6.7 2033.2503 APR 216.9 108.0 24.6 18.4 13.4 7.1 2033.3337 MAY 223.4 113.7 25.4 19.1 13.7 7.0 2033.4170 JUN 224.9 118.9 26.5 19.6 14.2 7.0 2033.5003 JUL 225.7 123.4 27.6 20.3 14.5 7.1 2033.5837 AUG 231.0 127.1 28.4 20.3 14.5 7.2 2033.6670 SEP 233.8 130.6 29.3 20.3 14.6 7.7 2033.7503 OCT 236.3 134.3 29.4 20.5 14.7 8.1 2033.8337 NOV 239.2 137.7 28.9 20.8 14.8 8.0 2033.9170 DEC 241.7 141.1 28.5 21.2 14.8 8.0 2034.0003 JAN 248.2 144.4 29.4 21.3 14.6 8.4 2034.0837 FEB 255.6 147.5 30.6 21.4 14.6 8.6 2034.1670 MAR 260.4 150.2 32.8 21.6 14.6 8.4 2034.2503 APR 264.8 153.0 36.1 22.0 14.5 8.4 2034.3337 MAY 269.5 155.4 38.1 22.7 14.4 8.6 2034.4170 JUN 272.7 157.2 40.4 22.4 14.1 8.6 2034.5003 JUL 274.4 158.0 44.2 21.3 13.8 8.5 2034.5837 AUG 275.1 158.0 48.5 20.6 13.7 8.3 2034.6670 SEP 276.4 158.8 52.8 20.1 13.6 8.0 2034.7503 OCT 276.2 160.2 54.7 19.7 13.5 7.6 2034.8337 NOV 275.2 161.0 56.7 19.6 13.5 7.5 2034.9170 DEC 276.2 161.2 60.3 19.3 13.5 7.8 2035.0003 JAN 275.3 160.2 62.7 19.1 13.7 7.7 2035.0837 FEB 269.5 158.5 66.2 18.9 13.9 7.6 2035.1670 MAR 263.0 157.1 68.8 18.9 14.0 7.5 2035.2503 APR 257.3 156.7 71.6 19.5 13.9 7.2 2035.3337 MAY 253.6 156.9 73.6 20.4 14.0 7.1 2035.4170 JUN 251.7 156.6 73.3 22.0 14.4 7.1 2035.5003 JUL 249.8 156.0 72.5 23.4 14.7 7.1 2035.5837 AUG 248.7 155.6 73.6 24.0 14.9 7.3 2035.6670 SEP 246.7 155.0 76.8 25.1 15.1 7.3 2035.7503 OCT 244.9 154.3 76.9 25.7 15.3 7.0 2035.8337 NOV 242.7 153.3 75.2 24.9 15.3 7.1 2035.9170 DEC 241.9 152.0 74.2 24.8 15.3 6.7 2036.0003 JAN 239.5 150.6 75.1 24.0 15.3 6.3 2036.0837 FEB 234.9 148.4 75.9 22.2 15.3 6.1 2036.1670 MAR 230.5 145.4 73.9 22.5 15.5 6.3 2036.2503 APR 226.5 142.7 73.2 23.2 15.7 6.5 2036.3337 MAY 222.0 140.7 74.9 23.2 15.7 6.7 2036.4170 JUN 216.0 138.6 76.5 22.7 15.7 7.1 2036.5003 JUL 210.7 135.7 74.5 22.0 15.6 7.6 2036.5837 AUG 205.8 132.7 71.2 21.9 15.7 7.7 2036.6670 SEP 202.0 130.3 69.5 22.7 15.9 8.1 2036.7503 OCT 200.2 128.2 68.9 23.6 16.2 8.7 2036.8337 NOV 194.9 125.5 65.8 23.8 16.4 8.9 2036.9170 DEC 191.9 122.7 58.8 23.8 16.6 9.3 2037.0003 JAN 189.9 119.8 57.2 23.8 16.6 9.7 2037.0837 FEB 185.1 117.3 59.1 23.4 16.6 10.1 2037.1670 MAR 179.7 115.3 57.6 22.5 16.5 10.5 2037.2503 APR 174.1 113.5 54.5 22.7 16.4 10.7 2037.3337 MAY 168.6 111.5 52.9 22.9 16.5 11.5 2037.4170 JUN 163.8 109.2 51.6 23.0 16.6 11.7 2037.5003 JUL 160.3 106.3 49.1 22.4 16.7 11.9 2037.5837 AUG 154.9 103.4 46.5 21.5 16.5 11.9 2037.6670 SEP 146.1 100.2 45.0 21.2 16.3 11.7 2037.7503 OCT 138.4 96.7 44.3 21.7 16.1 11.4 2037.8337 NOV 136.9 93.7 44.5 21.7 16.1 11.5 2037.9170 DEC 135.5 90.9 43.0 22.1 16.1 11.4 2038.0003 JAN 131.3 88.4 40.6 22.5 16.2 11.2 2038.0837 FEB 126.7 86.0 40.9 22.3 16.2 11.0 2038.1670 MAR 121.9 83.3 39.8 22.3 16.0 10.8 2038.2503 APR 116.7 80.6 37.9 22.7 15.8 10.7 2038.3337 MAY 115.9 78.0 36.5 22.9 15.5 10.6 2038.4170 JUN 116.7 75.4 34.0 23.4 15.3 10.3 2038.5003 JUL 115.2 72.7 31.6 24.0 15.0 10.1 2038.5837 AUG 113.7 70.1 27.9 24.7 14.9 10.1 2038.6670 SEP 111.2 67.9 24.9 25.3 14.8 10.1 2038.7503 OCT 107.6 65.9 22.9 25.4 14.8 10.5 2038.8337 NOV 103.7 64.0 20.0 25.3 14.7 10.4 2038.9170 DEC 100.4 61.7 17.6 24.8 14.5 10.2 2039.0003 JAN 99.3 59.5 16.1 23.9 14.3 10.0 2039.0837 FEB 98.1 57.6 14.9 23.0 14.1 9.4 2039.1670 MAR 95.1 55.6 13.6 22.5 14.2 8.8 2039.2503 APR 91.4 53.5 13.4 22.1 14.2 8.1 2039.3337 MAY 86.4 51.3 13.7 21.8 14.3 7.5 2039.4170 JUN 84.7 49.5 13.1 21.4 14.5 7.4 2039.5003 JUL 85.0 48.0 12.9 20.8 14.4 7.7 2039.5837 AUG 82.2 46.4 12.6 20.0 14.3 8.1 2039.6670 SEP 77.6 44.3 12.0 20.0 14.1 8.5 2039.7503 OCT 73.8 42.1 11.1 20.2 13.9 8.5 2039.8337 NOV 70.0 40.7 11.0 19.8 13.7 8.5 2039.9170 DEC 68.3 39.4 10.3 19.4 13.6 8.4 2040.0003 JAN 65.8 37.7 9.2 18.9 13.6 8.4 2040.0837 FEB 64.4 36.0 8.8 18.2 13.6 8.1 2040.1670 MAR 62.8 34.3 7.4 17.3 13.5 7.7 2040.2503 APR 61.9 32.8 6.0 17.3 13.3 7.1 2040.3337 MAY 60.4 31.1 5.9 17.4 13.2 6.8 2040.4170 JUN 58.5 29.7 5.8 17.5 13.1 6.6 2040.5003 JUL 56.4 28.3 5.6 17.5 12.9 6.5 2040.5837 AUG 54.1 26.9 5.4 17.7 12.9 6.6 2040.6670 SEP 51.2 25.4 4.3 18.0 12.7 6.5 2040.7503 OCT 48.1 24.0 3.3 17.9 12.6 6.4 2040.8337 NOV 43.8 22.8 2.9 17.6 12.3 6.4 2040.9170 DEC 38.5 21.2 2.7 17.3 12.0 6.2 2041.0003 JAN 34.9 19.3 2.1 16.3 11.7 6.1 2041.0837 FEB 33.1 17.6 1.5 14.9 11.2 6.0 2041.1670 MAR 32.1 16.2 1.2 13.8 10.9 6.1 2041.2503 APR 31.6 15.0 1.1 13.9 10.5 6.2 2041.3337 MAY 31.0 14.0 1.0 13.6 10.2 6.2 2041.4170 JUN 30.2 13.1 0.8 13.2 9.8 6.0 2041.5003 JUL 27.9 12.2 0.6 12.9 9.5 5.9 2041.5837 AUG 25.2 11.4 0.3 12.6 9.3 5.8 2041.6670 SEP 23.3 10.6 0.1 11.9 9.1 5.7 2041.7503 OCT 21.6 9.8 0.0 11.4 8.9 5.2