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% 2021.3337 MAY 30.8 27.2 24.1 7.4 6.7 5.8 2021.4170 JUN 38.4 29.8 22.4 8.2 6.9 5.4 2021.5003 JUL 47.5 33.2 21.1 8.3 7.1 5.2 2021.5837 AUG 57.0 37.6 22.2 8.7 7.3 5.2 2021.6670 SEP 65.4 42.1 24.7 8.7 7.4 5.7 2021.7503 OCT 74.2 46.8 28.0 9.6 7.5 5.9 2021.8337 NOV 85.2 51.5 30.8 10.2 7.6 5.9 2021.9170 DEC 97.1 55.7 32.0 10.4 7.8 6.2 2022.0003 JAN 107.8 60.6 33.2 10.8 8.0 6.5 2022.0837 FEB 117.9 65.7 35.4 11.5 8.3 6.6 2022.1670 MAR 128.6 70.4 37.4 12.5 8.9 6.9 2022.2503 APR 140.3 75.3 40.2 13.3 9.3 7.2 2022.3337 MAY 148.0 80.2 43.1 14.0 9.7 7.2 2022.4170 JUN 153.6 85.5 47.0 14.4 10.0 6.8 2022.5003 JUL 160.6 90.2 49.3 14.0 10.1 6.3 2022.5837 AUG 168.1 93.2 49.9 14.3 10.2 6.1 2022.6670 SEP 175.1 96.1 50.4 14.2 10.4 6.0 2022.7503 OCT 185.1 99.4 52.8 14.1 10.6 6.0 2022.8337 NOV 197.5 103.0 54.2 14.8 10.8 5.7 2022.9170 DEC 208.0 107.4 53.8 15.2 10.9 5.4 2023.0003 JAN 216.2 111.7 53.6 15.1 11.2 5.1 2023.0837 FEB 222.3 115.1 53.2 15.1 11.3 4.9 2023.1670 MAR 227.6 118.4 54.1 15.3 11.3 4.8 2023.2503 APR 233.6 121.6 56.7 15.7 11.3 4.7 2023.3337 MAY 238.8 124.4 58.1 16.6 11.2 4.6 2023.4170 JUN 240.7 126.7 58.6 16.7 11.2 4.6 2023.5003 JUL 239.2 128.7 61.1 16.4 11.3 5.1 2023.5837 AUG 236.9 130.6 63.9 16.3 11.5 5.8 2023.6670 SEP 239.1 132.8 65.3 16.0 11.5 6.2 2023.7503 OCT 240.1 134.6 64.0 15.4 11.4 6.3 2023.8337 NOV 241.0 136.3 65.5 15.4 11.4 6.5 2023.9170 DEC 241.9 137.3 69.2 15.1 11.4 6.5 2024.0003 JAN 242.0 137.0 70.2 14.6 11.4 6.6 2024.0837 FEB 237.9 136.4 71.5 15.1 11.5 7.3 2024.1670 MAR 233.4 136.4 75.4 15.3 11.3 7.6 2024.2503 APR 229.7 137.5 76.3 15.7 10.9 7.4 2024.3337 MAY 227.4 138.6 74.2 16.4 10.8 7.4 2024.4170 JUN 226.3 138.9 70.9 17.8 11.0 7.3 2024.5003 JUL 225.3 139.0 70.1 19.0 11.2 7.5 2024.5837 AUG 224.7 139.8 70.5 19.7 11.4 7.9 2024.6670 SEP 224.9 140.7 71.9 20.7 11.6 8.0 2024.7503 OCT 225.3 140.9 71.5 21.0 11.6 7.7 2024.8337 NOV 223.3 140.1 69.3 20.4 11.7 7.7 2024.9170 DEC 221.4 139.4 68.5 20.3 11.7 7.5 2025.0003 JAN 220.4 138.9 69.8 19.4 11.6 7.1 2025.0837 FEB 219.3 137.7 70.3 17.4 11.5 6.5 2025.1670 MAR 216.7 136.0 68.9 15.8 11.6 6.3 2025.2503 APR 214.4 134.4 68.9 15.9 11.9 6.5 2025.3337 MAY 211.0 133.1 68.7 16.2 12.1 6.8 2025.4170 JUN 205.8 131.8 68.1 16.8 12.2 7.2 2025.5003 JUL 201.8 129.7 67.8 17.2 12.3 7.3 2025.5837 AUG 198.3 127.6 65.7 16.8 12.1 6.9 2025.6670 SEP 198.0 126.0 64.5 17.0 12.0 6.8 2025.7503 OCT 197.0 124.8 64.6 17.3 12.2 7.3 2025.8337 NOV 192.5 123.0 64.2 17.2 12.2 7.5 2025.9170 DEC 190.0 120.6 58.9 16.6 12.3 7.4 2026.0003 JAN 188.4 118.2 57.3 15.7 12.4 7.3 2026.0837 FEB 183.8 115.9 58.6 15.6 12.5 7.2 2026.1670 MAR 178.2 113.8 55.1 16.2 12.8 7.6 2026.2503 APR 172.3 111.7 51.6 16.6 13.1 8.0 2026.3337 MAY 166.8 109.6 49.8 16.7 13.3 8.9 2026.4170 JUN 162.2 107.3 48.7 17.0 13.6 9.5 2026.5003 JUL 159.2 105.0 47.0 17.4 13.8 9.8 2026.5837 AUG 154.1 102.6 45.1 18.7 14.0 10.1 2026.6670 SEP 145.7 99.7 44.2 19.9 14.1 10.4 2026.7503 OCT 138.3 96.7 44.2 20.6 14.2 10.7 2026.8337 NOV 136.8 93.6 44.3 20.7 14.4 11.0 2026.9170 DEC 135.0 90.4 42.5 20.4 14.5 10.9 2027.0003 JAN 130.7 87.8 40.7 19.7 14.6 10.4 2027.0837 FEB 126.6 85.8 41.0 18.9 14.5 9.8 2027.1670 MAR 122.3 83.7 39.5 18.7 14.3 9.5 2027.2503 APR 117.5 81.5 37.2 18.8 14.0 9.1 2027.3337 MAY 115.9 79.2 35.6 18.7 13.6 8.4 2027.4170 JUN 116.5 76.8 34.1 18.8 13.1 7.1 2027.5003 JUL 115.1 73.7 31.7 19.0 12.7 6.0 2027.5837 AUG 113.5 71.0 28.3 19.1 12.2 5.6 2027.6670 SEP 111.1 68.8 25.4 19.3 12.0 5.4 2027.7503 OCT 107.5 66.4 22.8 19.5 12.0 5.3 2027.8337 NOV 104.0 64.3 19.9 19.1 11.7 5.1 2027.9170 DEC 100.3 62.1 17.5 18.4 11.5 5.2 2028.0003 JAN 99.2 60.4 15.8 17.7 11.4 5.5 2028.0837 FEB 98.0 58.9 14.5 17.2 11.4 6.0 2028.1670 MAR 94.5 57.4 13.3 17.2 11.6 5.7 2028.2503 APR 90.7 55.8 13.3 17.1 11.8 5.2 2028.3337 MAY 86.9 53.6 13.0 17.3 12.2 4.8 2028.4170 JUN 87.2 51.8 12.1 17.4 12.5 5.0 2028.5003 JUL 87.6 50.8 11.6 18.1 12.6 5.5 2028.5837 AUG 85.1 49.6 11.1 18.5 12.6 6.0 2028.6670 SEP 80.3 47.2 10.8 18.8 12.5 6.4 2028.7503 OCT 75.7 44.7 11.4 18.9 12.4 6.5 2028.8337 NOV 71.1 42.6 11.8 18.7 12.3 6.7 2028.9170 DEC 67.9 40.7 10.9 18.5 12.4 6.9 2029.0003 JAN 66.3 38.4 9.5 18.2 12.7 7.2 2029.0837 FEB 64.6 36.2 8.9 17.6 12.8 7.4 2029.1670 MAR 62.4 34.1 7.3 16.8 12.8 7.5 2029.2503 APR 60.7 32.1 5.6 17.1 12.6 7.3 2029.3337 MAY 59.0 30.3 5.4 17.2 12.4 7.0 2029.4170 JUN 57.1 28.8 5.3 17.3 12.3 6.8 2029.5003 JUL 55.2 27.6 5.2 17.3 12.3 6.5 2029.5837 AUG 53.3 26.4 5.2 17.6 12.4 6.5 2029.6670 SEP 50.7 25.2 4.5 17.9 12.5 6.5 2029.7503 OCT 47.8 23.9 3.4 17.9 12.4 6.4 2029.8337 NOV 43.7 22.7 2.9 17.6 12.2 6.4 2029.9170 DEC 38.7 21.3 2.7 17.3 11.9 6.2 2030.0003 JAN 35.0 19.5 2.0 16.2 11.5 6.1 2030.0837 FEB 33.3 17.9 1.3 14.7 10.9 6.1 2030.1670 MAR 32.4 16.6 0.9 13.5 10.5 6.2 2030.2503 APR 31.9 15.7 0.7 13.5 10.1 6.3 2030.3337 MAY 31.2 14.7 0.5 13.1 9.6 6.3 2030.4170 JUN 30.2 13.6 0.3 12.8 9.3 6.1 2030.5003 JUL 28.2 12.6 0.2 12.6 9.1 6.0 2030.5837 AUG 25.5 11.7 0.1 12.3 8.9 5.7 2030.6670 SEP 23.7 10.9 0.0 11.5 8.7 5.1 2030.7503 OCT 21.9 10.2 0.0 11.0 8.5 4.7 2030.8337 NOV 19.3 9.5 0.0 10.8 8.2 4.3 2030.9170 DEC 19.2 9.5 0.0 10.8 8.3 4.3 2031.0003 JAN 20.1 10.1 0.7 11.1 8.3 4.2 2031.0837 FEB 21.9 11.2 1.3 11.4 8.5 4.2 2031.1670 MAR 23.6 12.3 1.7 11.5 8.7 4.1 2031.2503 APR 26.1 13.2 2.3 11.8 8.8 3.8 2031.3337 MAY 28.9 14.4 2.5 11.9 8.9 3.7 2031.4170 JUN 33.4 15.9 3.2 12.0 9.0 3.6 2031.5003 JUL 36.9 17.6 4.4 12.2 9.1 3.5 2031.5837 AUG 40.5 19.4 5.0 12.5 9.3 3.4 2031.6670 SEP 45.9 21.5 5.6 12.8 9.6 3.5 2031.7503 OCT 52.8 23.8 6.1 13.3 10.0 3.8 2031.8337 NOV 63.1 26.6 6.1 13.8 10.3 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