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% 2020.6670 SEP 13.6 10.0 8.1 5.8 5.5 5.3 2020.7503 OCT 16.5 10.8 6.6 6.8 5.7 5.2 2020.8337 NOV 18.6 11.6 5.9 7.6 6.0 5.1 2020.9170 DEC 21.2 12.8 5.2 8.0 6.2 5.0 2021.0003 JAN 23.9 14.3 3.6 8.2 6.2 4.7 2021.0837 FEB 29.5 15.7 2.0 8.8 6.2 4.5 2021.1670 MAR 35.4 17.5 0.0 9.5 6.3 4.1 2021.2503 APR 41.6 19.9 0.0 10.3 6.4 3.7 2021.3337 MAY 49.6 22.1 0.0 11.5 6.7 3.6 2021.4170 JUN 59.2 24.3 0.0 12.4 7.0 3.7 2021.5003 JUL 68.8 27.7 0.1 12.7 7.2 3.7 2021.5837 AUG 78.2 32.2 0.7 12.7 7.4 3.7 2021.6670 SEP 87.0 36.8 2.5 12.1 7.3 3.7 2021.7503 OCT 96.0 41.6 6.2 11.5 7.2 3.8 2021.8337 NOV 106.8 46.1 9.5 10.9 7.1 4.0 2021.9170 DEC 118.2 50.2 10.6 10.5 7.2 4.0 2022.0003 JAN 128.4 55.0 11.9 10.5 7.3 4.3 2022.0837 FEB 137.4 59.6 13.5 10.5 7.6 5.1 2022.1670 MAR 148.3 63.8 14.6 10.8 7.9 5.5 2022.2503 APR 159.4 68.4 16.5 10.7 8.3 6.1 2022.3337 MAY 166.4 72.9 18.7 10.7 8.4 6.2 2022.4170 JUN 171.7 77.8 22.5 11.3 8.7 5.7 2022.5003 JUL 178.4 82.2 24.7 12.1 8.9 5.5 2022.5837 AUG 184.0 84.9 24.0 12.2 9.1 5.3 2022.6670 SEP 189.6 87.4 23.9 12.8 9.4 5.5 2022.7503 OCT 198.0 90.5 26.6 13.7 9.9 5.8 2022.8337 NOV 205.5 94.0 29.6 14.4 10.1 5.5 2022.9170 DEC 210.8 98.5 32.7 14.8 10.2 5.3 2023.0003 JAN 218.3 103.3 37.6 15.3 10.5 5.0 2023.0837 FEB 226.4 107.2 42.9 15.8 10.7 4.7 2023.1670 MAR 231.6 110.4 45.5 16.1 10.8 4.7 2023.2503 APR 236.1 113.4 47.9 16.7 10.9 4.8 2023.3337 MAY 240.8 115.9 48.8 17.7 10.9 4.9 2023.4170 JUN 244.5 118.3 48.1 17.9 11.0 5.0 2023.5003 JUL 247.4 120.8 48.7 17.3 11.1 5.3 2023.5837 AUG 250.1 123.5 51.5 16.9 11.2 5.8 2023.6670 SEP 252.9 126.4 54.5 16.4 11.1 6.0 2023.7503 OCT 253.2 128.4 57.3 15.8 10.9 6.0 2023.8337 NOV 253.0 130.4 60.2 15.8 10.9 6.2 2023.9170 DEC 254.8 131.8 61.7 15.6 11.0 6.3 2024.0003 JAN 254.7 131.8 62.0 14.9 10.8 6.2 2024.0837 FEB 250.3 132.0 62.1 14.1 10.7 6.5 2024.1670 MAR 245.5 133.0 62.9 13.4 10.3 6.7 2024.2503 APR 241.2 134.5 65.9 13.0 9.8 6.1 2024.3337 MAY 238.2 135.6 68.4 13.2 9.6 5.8 2024.4170 JUN 236.7 135.9 67.6 14.1 9.7 5.5 2024.5003 JUL 235.4 136.4 67.3 15.0 9.7 5.2 2024.5837 AUG 234.2 137.4 69.1 15.5 9.8 5.4 2024.6670 SEP 233.1 138.2 72.0 16.2 9.8 5.2 2024.7503 OCT 232.8 138.2 72.8 16.3 9.8 5.2 2024.8337 NOV 230.7 137.4 71.5 15.8 9.9 6.0 2024.9170 DEC 229.7 136.9 70.3 15.5 9.8 6.2 2025.0003 JAN 228.2 136.7 71.4 14.5 9.6 6.3 2025.0837 FEB 225.3 135.7 72.2 14.2 9.6 6.3 2025.1670 MAR 221.6 133.6 71.9 14.2 9.9 7.1 2025.2503 APR 218.1 131.6 70.7 15.1 10.2 7.3 2025.3337 MAY 213.8 129.8 69.4 15.2 10.4 7.4 2025.4170 JUN 207.7 128.0 67.3 15.6 10.7 7.3 2025.5003 JUL 203.0 125.8 66.4 16.1 10.9 7.5 2025.5837 AUG 198.8 123.5 64.1 15.2 10.6 7.3 2025.6670 SEP 194.9 122.2 62.6 15.0 10.7 7.2 2025.7503 OCT 194.0 121.4 62.8 16.0 11.1 7.1 2025.8337 NOV 189.7 119.9 62.2 16.0 11.1 7.2 2025.9170 DEC 187.1 117.4 57.8 15.9 11.2 7.0 2026.0003 JAN 185.7 115.2 56.3 16.0 11.3 7.0 2026.0837 FEB 181.2 113.1 56.2 16.1 11.6 6.9 2026.1670 MAR 175.3 110.6 52.5 15.4 12.0 7.4 2026.2503 APR 168.9 108.0 48.5 15.4 12.3 7.9 2026.3337 MAY 163.1 105.5 46.5 16.1 12.7 8.8 2026.4170 JUN 158.3 103.2 45.2 16.6 13.0 8.7 2026.5003 JUL 155.2 101.0 43.4 16.5 13.4 9.2 2026.5837 AUG 150.7 98.9 41.6 16.8 13.5 9.3 2026.6670 SEP 142.4 96.2 40.7 18.0 13.5 9.4 2026.7503 OCT 134.5 93.0 40.3 18.6 13.4 9.5 2026.8337 NOV 132.4 89.5 40.0 19.0 13.6 9.8 2026.9170 DEC 130.1 85.9 38.0 19.2 13.8 9.8 2027.0003 JAN 125.5 83.0 36.3 19.5 13.9 10.2 2027.0837 FEB 121.4 80.9 37.2 19.2 13.8 9.7 2027.1670 MAR 117.2 78.8 36.5 19.3 13.7 9.5 2027.2503 APR 113.4 76.9 35.7 19.7 13.6 9.4 2027.3337 MAY 114.6 75.1 32.3 19.9 13.3 8.9 2027.4170 JUN 115.8 73.3 30.3 20.3 12.9 7.9 2027.5003 JUL 114.2 70.4 27.5 20.8 12.5 7.0 2027.5837 AUG 112.7 67.8 24.7 21.4 12.3 7.1 2027.6670 SEP 110.4 65.9 23.3 22.0 12.3 7.2 2027.7503 OCT 106.6 63.6 21.6 22.3 12.4 7.2 2027.8337 NOV 102.6 61.7 19.1 22.1 12.1 7.2 2027.9170 DEC 99.6 59.9 16.8 21.5 11.9 7.1 2028.0003 JAN 98.9 58.5 15.6 20.7 11.8 6.5 2028.0837 FEB 98.0 57.3 14.7 20.0 11.8 6.1 2028.1670 MAR 95.2 55.9 13.9 19.8 12.1 5.9 2028.2503 APR 91.5 54.4 14.3 19.5 12.2 5.3 2028.3337 MAY 86.7 52.3 14.6 19.4 12.4 4.9 2028.4170 JUN 85.7 50.3 13.6 19.2 12.7 5.0 2028.5003 JUL 86.6 49.5 13.4 18.7 12.8 5.5 2028.5837 AUG 84.2 48.4 13.3 18.7 12.7 5.9 2028.6670 SEP 79.3 45.6 12.5 18.9 12.5 6.2 2028.7503 OCT 74.4 42.8 11.4 19.0 12.3 6.2 2028.8337 NOV 69.9 40.6 10.9 18.8 12.3 6.4 2028.9170 DEC 68.2 38.5 10.0 18.6 12.4 6.7 2029.0003 JAN 65.0 35.9 8.7 18.3 12.7 7.2 2029.0837 FEB 60.6 33.6 7.8 17.7 13.0 7.5 2029.1670 MAR 57.9 31.6 6.6 16.9 13.0 7.6 2029.2503 APR 56.1 29.5 5.0 16.9 12.7 7.4 2029.3337 MAY 54.3 27.7 4.7 16.9 12.5 7.1 2029.4170 JUN 52.7 26.4 4.6 16.9 12.2 6.8 2029.5003 JUL 51.1 25.3 4.3 17.1 12.2 6.3 2029.5837 AUG 49.4 24.2 4.2 17.5 12.4 6.4 2029.6670 SEP 47.2 23.2 3.5 17.8 12.3 6.6 2029.7503 OCT 44.2 22.1 2.6 17.8 12.2 6.5 2029.8337 NOV 40.8 21.3 2.3 17.5 12.0 6.5 2029.9170 DEC 36.3 20.1 2.4 17.2 11.7 6.3 2030.0003 JAN 34.0 18.5 1.9 16.1 11.2 6.3 2030.0837 FEB 32.5 17.1 1.4 14.5 10.6 6.4 2030.1670 MAR 31.7 15.8 1.1 13.2 10.1 6.2 2030.2503 APR 31.6 15.0 1.1 13.3 9.7 6.0 2030.3337 MAY 30.9 13.9 1.0 12.9 9.2 5.8 2030.4170 JUN 29.8 12.7 0.7 12.6 9.0 5.7 2030.5003 JUL 27.4 11.7 0.5 12.4 8.8 5.7 2030.5837 AUG 24.7 10.9 0.3 12.1 8.7 5.3 2030.6670 SEP 22.8 10.2 0.1 11.4 8.5 4.8 2030.7503 OCT 21.3 9.5 0.0 11.0 8.3 4.4 2030.8337 NOV 18.8 8.9 0.0 10.8 8.1 4.1 2030.9170 DEC 18.8 8.9 0.0 10.8 8.1 4.1 2031.0003 JAN 19.7 9.6 0.7 11.0 8.2 4.0 2031.0837 FEB 21.5 10.8 1.3 11.4 8.4 4.0 2031.1670 MAR 23.2 11.9 1.7 11.5 8.6 3.9 2031.2503 APR 25.8 12.9 2.3 11.7 8.7 3.7 2031.3337 MAY 28.6 14.1 2.5 11.9 8.8 3.5 2031.4170 JUN 33.2 15.7 3.2 12.0 8.9 3.5 2031.5003 JUL 36.7 17.4 4.4 12.1 9.0 3.4 2031.5837 AUG 40.4 19.3 5.0 12.5 9.3 3.4 2031.6670 SEP 45.8 21.4 5.6 12.8 9.6 3.4 2031.7503 OCT 52.8 23.7 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