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% 2021.6670 SEP 43.0 39.5 36.7 9.0 7.9 7.3 2021.7503 OCT 51.6 44.0 37.8 10.3 8.1 7.1 2021.8337 NOV 61.4 48.2 37.6 10.8 8.1 6.8 2021.9170 DEC 72.0 52.0 38.0 11.2 8.3 6.5 2022.0003 JAN 81.9 56.5 38.6 11.5 8.5 6.6 2022.0837 FEB 90.9 61.2 42.8 12.2 8.9 6.5 2022.1670 MAR 100.5 65.4 44.9 13.2 9.4 6.7 2022.2503 APR 111.2 69.9 44.5 14.0 9.9 6.9 2022.3337 MAY 121.2 74.6 44.9 14.7 10.3 7.2 2022.4170 JUN 132.1 79.7 46.1 15.1 10.6 7.6 2022.5003 JUL 142.0 84.2 47.2 14.8 10.7 7.7 2022.5837 AUG 149.8 87.1 48.3 15.0 10.7 7.4 2022.6670 SEP 156.5 89.9 48.9 14.8 10.9 7.2 2022.7503 OCT 166.1 93.0 45.8 14.2 11.1 7.1 2022.8337 NOV 178.2 96.3 43.2 14.7 11.2 6.6 2022.9170 DEC 188.8 100.4 41.3 15.0 11.2 6.2 2023.0003 JAN 196.8 104.3 39.2 15.0 11.4 5.8 2023.0837 FEB 202.8 107.6 38.0 15.4 11.6 5.5 2023.1670 MAR 208.3 110.9 38.5 15.4 11.5 5.3 2023.2503 APR 214.3 114.0 41.3 15.3 11.4 5.2 2023.3337 MAY 219.7 116.9 42.4 16.1 11.3 4.9 2023.4170 JUN 222.0 119.4 41.6 16.2 11.2 4.7 2023.5003 JUL 221.0 121.4 43.0 15.9 11.3 5.2 2023.5837 AUG 219.3 123.3 44.1 15.8 11.5 5.8 2023.6670 SEP 220.9 125.4 46.7 15.5 11.5 6.3 2023.7503 OCT 223.0 127.2 49.8 15.1 11.4 6.5 2023.8337 NOV 224.1 128.9 52.6 15.0 11.4 6.6 2023.9170 DEC 223.3 130.0 54.3 14.8 11.4 6.7 2024.0003 JAN 218.8 129.7 53.8 14.9 11.4 6.8 2024.0837 FEB 212.9 129.3 55.1 15.4 11.6 7.5 2024.1670 MAR 210.0 129.6 57.4 15.5 11.4 7.9 2024.2503 APR 208.8 131.0 58.9 15.9 11.1 7.2 2024.3337 MAY 205.9 132.3 58.6 16.7 11.0 7.5 2024.4170 JUN 204.2 132.8 57.7 18.1 11.2 7.9 2024.5003 JUL 204.0 133.1 55.9 19.3 11.4 8.0 2024.5837 AUG 204.8 134.0 54.2 20.0 11.6 8.0 2024.6670 SEP 206.4 135.2 54.6 21.0 11.8 7.7 2024.7503 OCT 206.8 135.6 53.7 21.4 11.9 7.2 2024.8337 NOV 205.0 135.1 52.4 20.7 11.9 7.2 2024.9170 DEC 205.5 134.6 52.2 20.7 12.0 7.1 2025.0003 JAN 204.9 134.1 53.4 19.9 12.0 6.8 2025.0837 FEB 202.9 132.9 53.7 18.0 11.9 6.4 2025.1670 MAR 201.1 131.1 54.3 16.4 12.1 6.3 2025.2503 APR 199.6 129.7 55.9 16.2 12.5 6.7 2025.3337 MAY 197.1 128.6 57.2 16.5 12.7 7.1 2025.4170 JUN 192.8 127.5 58.4 17.3 12.8 7.6 2025.5003 JUL 189.7 125.6 58.8 18.1 12.9 7.8 2025.5837 AUG 189.0 123.6 58.6 18.9 12.8 7.5 2025.6670 SEP 191.2 122.2 58.8 19.3 12.8 7.5 2025.7503 OCT 191.5 121.0 59.9 19.7 13.0 7.9 2025.8337 NOV 187.7 119.4 59.9 19.6 13.0 7.7 2025.9170 DEC 184.7 117.0 55.8 19.1 13.2 7.6 2026.0003 JAN 183.0 114.5 54.1 18.1 13.2 7.5 2026.0837 FEB 179.0 112.4 54.1 16.8 13.2 7.4 2026.1670 MAR 174.1 110.6 51.1 16.9 13.4 7.7 2026.2503 APR 168.6 108.8 48.1 17.2 13.7 8.2 2026.3337 MAY 163.2 106.9 46.6 17.6 13.9 9.0 2026.4170 JUN 159.2 104.9 45.8 17.7 14.0 9.6 2026.5003 JUL 156.4 102.7 44.2 18.1 14.2 9.8 2026.5837 AUG 151.2 100.2 42.1 19.3 14.3 10.1 2026.6670 SEP 142.7 97.4 41.1 20.4 14.4 10.4 2026.7503 OCT 135.7 94.5 41.3 21.0 14.4 10.9 2026.8337 NOV 133.9 91.6 41.7 21.1 14.6 11.5 2026.9170 DEC 132.1 88.5 40.1 20.7 14.6 10.9 2027.0003 JAN 127.9 86.0 38.8 20.1 14.7 10.3 2027.0837 FEB 124.6 84.2 40.4 19.3 14.6 9.7 2027.1670 MAR 120.8 82.3 40.6 18.3 14.4 9.3 2027.2503 APR 116.4 80.3 38.1 18.3 14.0 8.8 2027.3337 MAY 115.8 78.1 36.5 18.3 13.6 8.2 2027.4170 JUN 116.6 75.8 34.1 18.4 13.3 6.9 2027.5003 JUL 115.2 72.8 31.6 18.5 12.8 5.7 2027.5837 AUG 113.7 70.1 28.0 18.4 12.3 5.2 2027.6670 SEP 111.2 68.1 25.0 18.5 12.0 4.9 2027.7503 OCT 107.6 65.6 22.8 18.6 11.9 4.7 2027.8337 NOV 103.7 63.5 20.2 18.1 11.7 4.5 2027.9170 DEC 100.5 61.2 17.8 17.5 11.5 4.7 2028.0003 JAN 99.3 59.4 16.2 16.9 11.4 5.0 2028.0837 FEB 98.1 58.0 14.8 16.4 11.4 5.5 2028.1670 MAR 94.8 56.4 13.7 16.3 11.6 5.8 2028.2503 APR 91.0 54.8 13.7 16.1 11.8 6.0 2028.3337 MAY 86.0 52.6 13.8 17.1 12.1 5.6 2028.4170 JUN 85.8 50.8 12.8 17.4 12.3 5.6 2028.5003 JUL 86.3 49.8 12.4 17.7 12.4 6.1 2028.5837 AUG 83.8 48.7 11.9 18.1 12.4 6.6 2028.6670 SEP 79.1 46.4 11.4 18.4 12.4 7.0 2028.7503 OCT 74.6 43.9 11.6 18.6 12.2 7.0 2028.8337 NOV 70.1 41.9 11.3 18.4 12.2 7.1 2028.9170 DEC 68.1 40.0 10.5 18.1 12.3 7.2 2029.0003 JAN 65.8 37.8 9.3 17.8 12.4 7.4 2029.0837 FEB 64.1 35.7 8.8 17.2 12.5 7.5 2029.1670 MAR 62.2 33.6 7.2 16.9 12.5 7.4 2029.2503 APR 60.5 31.6 5.6 17.2 12.3 7.3 2029.3337 MAY 58.9 29.8 5.4 17.3 12.1 7.1 2029.4170 JUN 57.0 28.3 5.3 17.4 12.0 7.0 2029.5003 JUL 55.0 27.1 5.2 17.4 11.9 6.5 2029.5837 AUG 52.9 25.9 5.1 17.5 12.1 6.4 2029.6670 SEP 50.4 24.6 4.6 17.7 12.1 6.7 2029.7503 OCT 47.3 23.3 3.6 17.6 12.0 6.5 2029.8337 NOV 43.0 22.2 3.1 17.4 11.9 6.5 2029.9170 DEC 37.9 20.7 2.9 17.1 11.6 6.3 2030.0003 JAN 34.6 19.0 2.3 16.0 11.2 6.3 2030.0837 FEB 32.7 17.3 1.7 14.5 10.7 6.2 2030.1670 MAR 32.0 16.0 1.3 13.3 10.3 6.3 2030.2503 APR 31.6 15.1 1.0 13.4 10.0 6.4 2030.3337 MAY 31.0 14.1 0.9 13.0 9.6 6.4 2030.4170 JUN 30.2 13.0 0.8 12.6 9.3 6.2 2030.5003 JUL 27.8 12.0 0.7 12.4 9.0 6.1 2030.5837 AUG 25.0 11.1 0.5 12.1 8.8 5.8 2030.6670 SEP 23.0 10.3 0.3 11.3 8.5 5.2 2030.7503 OCT 21.5 9.6 0.2 11.0 8.3 4.7 2030.8337 NOV 18.9 8.9 0.2 10.6 8.1 4.4 2030.9170 DEC 18.9 9.0 0.2 10.6 8.1 4.4 2031.0003 JAN 19.8 9.6 0.9 10.9 8.2 4.2 2031.0837 FEB 21.6 10.8 1.5 11.2 8.4 4.2 2031.1670 MAR 23.3 11.9 1.8 11.4 8.6 4.1 2031.2503 APR 25.9 12.9 2.4 11.6 8.7 3.9 2031.3337 MAY 28.7 14.1 2.6 11.8 8.8 3.7 2031.4170 JUN 33.3 15.7 3.3 11.9 8.9 3.6 2031.5003 JUL 36.8 17.4 4.4 12.1 9.0 3.5 2031.5837 AUG 40.4 19.3 5.0 12.4 9.3 3.4 2031.6670 SEP 45.9 21.4 5.6 12.8 9.5 3.5 2031.7503 OCT 52.8 23.7 6.1 13.2 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