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% 2020.2503 APR 5.8 3.7 1.8 5.4 5.2 5.0 2020.3337 MAY 7.9 4.2 0.6 5.9 5.3 4.8 2020.4170 JUN 11.2 4.9 0.2 6.4 5.3 4.5 2020.5003 JUL 14.2 6.1 0.5 6.9 5.3 4.2 2020.5837 AUG 17.0 7.5 0.3 7.4 5.3 4.0 2020.6670 SEP 21.0 8.7 0.0 7.6 5.3 3.9 2020.7503 OCT 25.9 9.7 0.0 7.8 5.5 3.9 2020.8337 NOV 32.2 10.7 0.0 8.0 5.7 4.0 2020.9170 DEC 37.5 12.1 0.0 8.1 5.8 4.3 2021.0003 JAN 41.2 13.6 0.0 8.1 5.7 4.0 2021.0837 FEB 46.8 15.1 0.0 8.0 5.6 3.7 2021.1670 MAR 54.7 17.3 0.0 8.1 5.6 3.5 2021.2503 APR 63.5 20.1 0.0 8.6 5.6 3.0 2021.3337 MAY 72.8 22.7 0.0 9.6 5.7 2.7 2021.4170 JUN 83.6 25.3 0.0 10.4 5.9 2.7 2021.5003 JUL 91.9 28.6 0.0 10.6 6.0 2.6 2021.5837 AUG 98.0 32.6 0.0 10.5 6.1 2.6 2021.6670 SEP 104.0 36.8 0.0 10.0 6.1 2.6 2021.7503 OCT 110.8 41.4 0.0 9.4 6.1 2.8 2021.8337 NOV 120.0 45.4 0.0 8.8 6.0 3.0 2021.9170 DEC 131.8 49.4 0.0 8.3 6.1 3.1 2022.0003 JAN 142.4 54.1 0.0 8.7 6.3 3.4 2022.0837 FEB 151.1 58.1 0.8 9.8 6.7 4.4 2022.1670 MAR 160.8 61.8 1.7 10.2 7.2 5.0 2022.2503 APR 169.7 65.9 4.2 10.2 7.6 5.2 2022.3337 MAY 174.4 69.4 5.7 10.3 7.8 5.4 2022.4170 JUN 175.4 73.1 7.8 10.9 8.1 4.9 2022.5003 JUL 178.3 76.8 10.0 11.6 8.2 4.5 2022.5837 AUG 182.3 79.1 10.8 11.7 8.3 4.3 2022.6670 SEP 186.3 81.6 11.7 12.3 8.7 4.5 2022.7503 OCT 194.7 84.5 11.3 13.2 9.2 4.8 2022.8337 NOV 201.1 87.2 9.5 13.9 9.3 4.4 2022.9170 DEC 205.3 90.3 10.8 14.1 9.3 4.0 2023.0003 JAN 212.2 94.0 12.7 14.1 9.7 3.7 2023.0837 FEB 219.6 97.1 14.3 13.8 10.0 3.6 2023.1670 MAR 223.8 98.9 16.5 13.7 10.0 3.5 2023.2503 APR 226.7 99.7 15.9 14.1 10.0 3.5 2023.3337 MAY 230.0 100.2 14.6 14.9 9.9 3.2 2023.4170 JUN 232.9 101.5 14.0 15.1 9.8 3.2 2023.5003 JUL 235.3 103.3 14.7 14.7 10.0 3.7 2023.5837 AUG 237.7 105.4 17.6 14.6 10.2 4.2 2023.6670 SEP 240.6 107.5 19.7 14.1 10.2 4.6 2023.7503 OCT 239.5 108.2 20.6 13.5 10.0 4.6 2023.8337 NOV 238.3 109.2 23.0 13.5 10.0 4.8 2023.9170 DEC 239.9 110.3 25.7 13.4 10.1 4.9 2024.0003 JAN 240.4 110.6 28.3 12.9 9.8 4.6 2024.0837 FEB 236.8 111.8 32.2 12.6 9.7 4.9 2024.1670 MAR 231.9 113.6 37.2 12.2 9.2 5.0 2024.2503 APR 227.9 115.6 42.3 12.1 8.7 4.9 2024.3337 MAY 224.9 116.7 46.1 12.3 8.6 4.7 2024.4170 JUN 223.8 117.0 48.7 13.3 8.6 4.4 2024.5003 JUL 223.9 117.9 51.0 14.2 8.6 4.3 2024.5837 AUG 222.9 119.6 53.9 14.7 8.7 4.6 2024.6670 SEP 220.8 120.9 58.0 15.4 8.7 4.6 2024.7503 OCT 220.6 121.5 59.4 15.5 8.6 4.4 2024.8337 NOV 220.4 121.6 58.7 15.0 8.8 4.7 2024.9170 DEC 220.9 121.8 58.7 15.0 8.9 4.7 2025.0003 JAN 219.8 122.4 60.9 14.1 8.8 5.6 2025.0837 FEB 216.0 121.7 62.3 12.7 8.8 5.7 2025.1670 MAR 209.8 119.0 62.3 12.8 9.1 5.8 2025.2503 APR 205.8 116.5 60.2 13.2 9.5 5.9 2025.3337 MAY 201.2 114.3 57.3 13.9 9.8 6.2 2025.4170 JUN 195.2 112.1 54.9 15.0 10.2 6.8 2025.5003 JUL 190.2 109.6 54.1 16.0 10.5 7.3 2025.5837 AUG 185.4 106.7 51.4 16.8 10.4 7.1 2025.6670 SEP 181.0 105.0 49.6 17.2 10.4 6.9 2025.7503 OCT 178.3 104.6 50.3 17.7 10.7 7.0 2025.8337 NOV 173.5 103.5 50.7 17.6 10.7 6.9 2025.9170 DEC 169.2 100.6 48.0 17.0 10.7 6.7 2026.0003 JAN 165.4 98.2 46.5 16.0 10.7 6.5 2026.0837 FEB 161.0 96.4 45.0 14.7 10.7 6.4 2026.1670 MAR 156.8 94.0 41.4 14.1 11.2 6.9 2026.2503 APR 152.3 91.6 38.2 14.2 11.6 7.4 2026.3337 MAY 148.1 89.4 36.8 14.9 11.9 8.2 2026.4170 JUN 142.5 87.0 35.0 15.0 12.0 7.8 2026.5003 JUL 136.2 84.7 32.8 14.6 12.2 8.0 2026.5837 AUG 130.7 83.1 31.2 15.6 12.3 8.5 2026.6670 SEP 124.7 81.1 30.1 16.9 12.4 8.8 2026.7503 OCT 119.6 78.1 28.8 17.8 12.5 9.8 2026.8337 NOV 116.0 74.2 27.2 18.2 12.9 9.2 2026.9170 DEC 112.2 69.9 24.7 18.1 13.1 9.0 2027.0003 JAN 105.8 66.1 22.3 18.5 13.3 8.7 2027.0837 FEB 99.8 63.7 21.5 18.5 13.4 8.3 2027.1670 MAR 101.7 61.5 18.9 18.6 13.3 8.2 2027.2503 APR 103.6 59.8 14.9 19.1 13.2 8.2 2027.3337 MAY 105.0 58.3 11.9 19.4 13.1 7.9 2027.4170 JUN 105.8 57.0 10.5 19.9 12.8 7.0 2027.5003 JUL 103.8 54.6 8.4 20.4 12.4 6.0 2027.5837 AUG 102.7 52.5 6.8 20.7 12.0 5.8 2027.6670 SEP 100.7 50.8 5.6 21.0 11.8 5.6 2027.7503 OCT 96.0 48.5 4.0 21.3 11.7 5.5 2027.8337 NOV 92.7 46.9 2.9 20.9 11.4 5.4 2027.9170 DEC 91.1 45.5 1.8 20.2 11.1 5.3 2028.0003 JAN 91.8 44.8 1.3 19.2 10.9 5.4 2028.0837 FEB 92.3 44.1 1.1 18.5 10.9 5.7 2028.1670 MAR 90.1 43.2 1.3 18.2 11.1 6.0 2028.2503 APR 86.8 42.1 2.5 17.9 11.2 5.5 2028.3337 MAY 81.9 40.2 3.3 17.7 11.4 5.0 2028.4170 JUN 76.8 38.2 2.9 17.5 11.6 5.0 2028.5003 JUL 76.5 37.4 3.2 17.7 11.8 5.5 2028.5837 AUG 75.4 36.6 4.4 18.1 11.8 6.1 2028.6670 SEP 70.4 34.1 4.5 18.4 11.7 6.4 2028.7503 OCT 66.2 31.6 2.7 18.5 11.5 6.4 2028.8337 NOV 64.8 30.0 1.7 18.3 11.6 6.6 2028.9170 DEC 63.8 28.4 2.5 18.1 11.7 6.8 2029.0003 JAN 60.6 26.5 2.9 17.8 12.1 7.1 2029.0837 FEB 55.8 24.7 2.4 17.2 12.3 7.3 2029.1670 MAR 51.3 22.9 1.2 16.4 12.2 7.2 2029.2503 APR 48.9 21.1 0.2 16.4 11.9 7.0 2029.3337 MAY 46.8 19.7 0.2 16.4 11.6 6.9 2029.4170 JUN 44.7 18.8 0.3 16.4 11.3 6.5 2029.5003 JUL 42.6 18.1 0.2 16.4 11.2 5.9 2029.5837 AUG 39.7 17.2 0.2 16.8 11.4 5.8 2029.6670 SEP 36.7 16.5 0.0 17.2 11.5 6.2 2029.7503 OCT 34.5 15.8 0.0 17.2 11.4 6.6 2029.8337 NOV 33.9 15.5 0.0 17.0 11.3 6.6 2029.9170 DEC 32.1 14.6 0.0 16.7 11.1 6.4 2030.0003 JAN 29.8 13.4 0.0 15.6 10.6 6.3 2030.0837 FEB 27.6 12.5 0.0 14.1 10.0 6.3 2030.1670 MAR 27.0 11.7 0.0 12.9 9.6 6.2 2030.2503 APR 27.2 11.3 0.0 13.0 9.2 6.1 2030.3337 MAY 26.6 10.4 0.0 12.7 8.9 5.9 2030.4170 JUN 25.4 9.3 0.0 12.3 8.6 5.8 2030.5003 JUL 23.7 8.5 0.0 12.1 8.5 5.7 2030.5837 AUG 21.2 7.8 0.0 11.8 8.3 5.3 2030.6670 SEP 18.7 7.3 0.0 11.1 7.9 4.7 2030.7503 OCT 17.2 6.8 0.0 10.5 7.7 4.2 2030.8337 NOV 15.1 6.4 0.0 10.3 7.5 3.9 2030.9170 DEC 15.4 6.6 0.0 10.4 7.6 3.9 2031.0003 JAN 16.6 7.5 0.7 10.7 7.7 3.8 2031.0837 FEB 18.7 8.9 1.3 11.0 8.0 3.9 2031.1670 MAR 20.7 10.2 1.7 11.2 8.2 3.8 2031.2503 APR 23.6 11.5 2.3 11.5 8.3 3.6 2031.3337 MAY 26.8 12.8 2.5 11.7 8.5 3.4 2031.4170 JUN 31.7 14.7 3.2 11.8 8.7 3.4 2031.5003 JUL 35.5 16.6 4.4 12.0 8.8 3.4 2031.5837 AUG 39.5 18.7 5.0 12.4 9.1 3.3 2031.6670 SEP 45.2 21.0 5.6 12.8 9.5 3.4 2031.7503 OCT 52.5 23.5 6.1 13.2 9.9 3.7 2031.8337 NOV 63.0 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