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% 2020.1670 MAR 5.9 3.8 2.2 5.6 5.4 5.2 2020.2503 APR 8.8 4.6 2.2 5.7 5.3 5.0 2020.3337 MAY 11.4 5.3 1.2 6.0 5.4 4.8 2020.4170 JUN 15.2 6.1 1.3 6.5 5.4 4.5 2020.5003 JUL 18.5 7.5 1.2 7.0 5.4 4.2 2020.5837 AUG 21.6 9.0 0.6 7.6 5.4 4.1 2020.6670 SEP 25.7 10.3 0.2 7.8 5.4 3.9 2020.7503 OCT 31.0 11.7 0.1 7.9 5.6 3.9 2020.8337 NOV 38.7 13.1 0.0 8.1 5.8 4.0 2020.9170 DEC 44.8 14.8 0.0 8.2 5.9 4.2 2021.0003 JAN 49.1 16.6 0.0 8.2 5.8 4.2 2021.0837 FEB 56.0 18.4 0.0 8.2 5.7 3.8 2021.1670 MAR 64.2 20.9 0.0 8.2 5.7 3.5 2021.2503 APR 73.2 24.0 0.0 8.4 5.6 3.0 2021.3337 MAY 83.8 27.0 0.0 9.3 5.7 2.7 2021.4170 JUN 95.7 30.1 0.0 10.1 5.9 2.7 2021.5003 JUL 104.7 33.6 0.0 10.2 6.0 2.6 2021.5837 AUG 111.1 37.6 0.0 10.1 6.1 2.6 2021.6670 SEP 117.4 41.9 0.0 9.6 6.1 2.6 2021.7503 OCT 124.4 46.5 0.0 9.1 6.1 2.8 2021.8337 NOV 131.8 50.6 0.2 8.5 6.1 3.0 2021.9170 DEC 140.7 54.7 1.9 8.1 6.1 3.1 2022.0003 JAN 151.5 59.5 3.9 8.5 6.4 3.5 2022.0837 FEB 160.5 63.6 5.9 9.7 6.7 4.5 2022.1670 MAR 170.5 67.4 6.9 10.1 7.2 5.0 2022.2503 APR 179.6 71.5 9.3 10.1 7.6 5.2 2022.3337 MAY 184.7 75.0 10.5 10.4 7.9 5.5 2022.4170 JUN 185.7 78.6 12.2 10.8 8.1 5.1 2022.5003 JUL 188.6 82.1 14.1 11.4 8.3 4.7 2022.5837 AUG 192.9 84.6 15.0 11.6 8.4 4.6 2022.6670 SEP 196.9 87.1 16.7 12.2 8.8 4.7 2022.7503 OCT 203.5 90.1 16.1 13.0 9.2 4.9 2022.8337 NOV 208.6 92.6 13.8 13.7 9.3 4.5 2022.9170 DEC 211.7 95.1 14.0 13.9 9.3 4.1 2023.0003 JAN 218.2 98.4 15.1 13.9 9.7 3.8 2023.0837 FEB 225.4 101.2 16.3 13.6 10.0 3.6 2023.1670 MAR 229.6 102.8 18.2 13.5 10.0 3.6 2023.2503 APR 232.6 103.6 18.1 13.8 9.9 3.5 2023.3337 MAY 236.0 104.0 16.5 14.6 9.8 3.2 2023.4170 JUN 238.9 105.2 15.2 14.7 9.7 3.1 2023.5003 JUL 241.0 106.8 15.7 14.4 9.9 3.6 2023.5837 AUG 242.8 108.5 18.9 14.3 10.1 4.2 2023.6670 SEP 245.0 110.4 20.9 13.9 10.1 4.5 2023.7503 OCT 244.2 111.0 21.7 13.3 9.9 4.6 2023.8337 NOV 243.2 111.9 24.0 13.2 9.9 4.7 2023.9170 DEC 244.7 112.9 26.5 13.3 10.0 4.9 2024.0003 JAN 244.6 113.1 29.1 12.8 9.8 4.7 2024.0837 FEB 240.6 114.1 32.9 12.6 9.7 4.9 2024.1670 MAR 236.0 115.7 37.7 12.1 9.3 5.2 2024.2503 APR 231.7 117.5 42.7 12.0 8.8 5.1 2024.3337 MAY 228.6 118.5 46.4 12.5 8.7 4.9 2024.4170 JUN 227.7 118.8 49.1 13.6 8.7 4.6 2024.5003 JUL 227.0 119.4 52.0 14.5 8.7 4.6 2024.5837 AUG 225.7 120.8 55.4 15.0 8.8 4.9 2024.6670 SEP 223.6 121.9 59.1 15.8 8.8 5.0 2024.7503 OCT 223.2 122.4 60.6 15.9 8.8 4.8 2024.8337 NOV 223.0 122.6 60.0 15.4 9.0 5.0 2024.9170 DEC 223.4 122.7 60.0 15.4 9.0 5.1 2025.0003 JAN 222.1 123.2 62.2 14.6 9.0 5.7 2025.0837 FEB 218.0 122.3 64.2 12.8 9.0 5.6 2025.1670 MAR 211.8 119.5 64.3 12.8 9.3 5.6 2025.2503 APR 207.7 116.9 62.1 13.3 9.6 5.8 2025.3337 MAY 203.6 114.6 59.3 14.1 9.9 6.1 2025.4170 JUN 197.6 112.4 56.3 15.2 10.3 6.7 2025.5003 JUL 192.6 109.9 54.6 16.1 10.6 7.2 2025.5837 AUG 187.2 107.0 51.9 16.9 10.5 7.0 2025.6670 SEP 182.7 105.2 50.0 17.3 10.5 7.0 2025.7503 OCT 179.4 104.7 50.5 17.8 10.8 7.0 2025.8337 NOV 174.5 103.5 50.8 17.8 10.8 6.9 2025.9170 DEC 169.7 100.7 48.1 17.1 10.8 6.7 2026.0003 JAN 165.7 98.1 45.8 16.1 10.8 6.5 2026.0837 FEB 161.3 96.2 44.3 14.8 10.9 6.4 2026.1670 MAR 157.2 94.0 40.8 14.2 11.3 6.9 2026.2503 APR 153.3 91.8 37.9 14.5 11.7 7.4 2026.3337 MAY 149.7 89.8 36.6 15.1 11.9 8.3 2026.4170 JUN 144.2 87.4 34.8 15.2 12.0 8.0 2026.5003 JUL 137.0 85.1 32.7 14.7 12.2 8.2 2026.5837 AUG 131.4 83.5 30.9 15.6 12.3 8.7 2026.6670 SEP 125.9 81.5 30.1 16.9 12.5 9.0 2026.7503 OCT 121.0 78.5 28.8 17.8 12.6 9.7 2026.8337 NOV 115.3 74.6 27.2 18.3 12.9 9.1 2026.9170 DEC 111.2 70.3 24.7 18.1 13.2 8.9 2027.0003 JAN 105.3 66.5 22.3 18.5 13.4 8.7 2027.0837 FEB 103.5 64.2 22.2 18.4 13.5 8.3 2027.1670 MAR 105.6 62.0 20.4 18.5 13.4 8.1 2027.2503 APR 107.3 60.3 16.3 19.0 13.3 8.1 2027.3337 MAY 108.6 58.7 13.2 19.3 13.1 7.9 2027.4170 JUN 109.1 57.3 12.1 19.8 12.8 7.0 2027.5003 JUL 107.1 55.1 10.2 20.3 12.4 6.0 2027.5837 AUG 106.0 53.1 8.7 20.6 12.0 5.7 2027.6670 SEP 103.9 51.4 7.5 20.9 11.8 5.5 2027.7503 OCT 99.2 49.2 5.9 21.1 11.7 5.4 2027.8337 NOV 95.5 47.4 4.7 20.8 11.4 5.2 2027.9170 DEC 93.8 46.0 3.4 20.0 11.1 5.1 2028.0003 JAN 94.2 45.1 2.6 19.0 10.9 5.2 2028.0837 FEB 94.5 44.4 2.3 18.3 10.9 5.6 2028.1670 MAR 92.1 43.4 2.4 18.1 11.1 5.9 2028.2503 APR 88.6 42.3 3.4 17.7 11.1 5.5 2028.3337 MAY 83.7 40.3 4.2 17.5 11.4 5.0 2028.4170 JUN 78.6 38.5 4.0 17.3 11.6 5.0 2028.5003 JUL 77.3 37.6 4.1 17.7 11.8 5.5 2028.5837 AUG 76.4 36.7 5.1 18.1 11.8 6.1 2028.6670 SEP 72.1 34.2 5.3 18.3 11.7 6.4 2028.7503 OCT 67.9 31.8 3.8 18.4 11.5 6.4 2028.8337 NOV 66.6 30.4 2.9 18.3 11.5 6.6 2028.9170 DEC 65.7 29.1 4.0 18.1 11.7 6.8 2029.0003 JAN 62.6 27.3 4.2 17.8 12.1 7.1 2029.0837 FEB 57.8 25.6 3.7 17.2 12.2 7.3 2029.1670 MAR 53.3 23.8 2.6 16.3 12.2 7.2 2029.2503 APR 50.3 22.1 1.2 16.5 11.9 7.0 2029.3337 MAY 47.8 20.6 0.8 16.5 11.6 6.9 2029.4170 JUN 45.6 19.7 1.1 16.5 11.4 6.5 2029.5003 JUL 43.5 18.9 1.1 16.6 11.3 6.0 2029.5837 AUG 40.4 17.9 1.1 16.8 11.4 5.9 2029.6670 SEP 37.1 16.9 0.1 17.2 11.5 6.2 2029.7503 OCT 35.3 16.2 0.0 17.2 11.5 6.6 2029.8337 NOV 34.6 15.7 0.0 17.0 11.3 6.6 2029.9170 DEC 32.7 14.7 0.0 16.7 11.1 6.4 2030.0003 JAN 29.9 13.4 0.0 15.6 10.6 6.3 2030.0837 FEB 27.4 12.5 0.0 14.1 10.0 6.3 2030.1670 MAR 26.5 11.7 0.0 12.9 9.6 6.2 2030.2503 APR 26.7 11.3 0.0 13.0 9.3 6.1 2030.3337 MAY 26.1 10.4 0.0 12.7 8.9 5.9 2030.4170 JUN 25.1 9.3 0.0 12.3 8.6 5.8 2030.5003 JUL 23.2 8.4 0.0 12.1 8.5 5.7 2030.5837 AUG 20.7 7.8 0.0 11.8 8.3 5.3 2030.6670 SEP 18.2 7.3 0.0 11.0 8.0 4.7 2030.7503 OCT 16.8 6.8 0.0 10.5 7.7 4.2 2030.8337 NOV 14.8 6.3 0.0 10.3 7.5 3.9 2030.9170 DEC 15.1 6.6 0.0 10.4 7.6 4.0 2031.0003 JAN 16.4 7.5 0.7 10.7 7.7 3.8 2031.0837 FEB 18.5 8.8 1.3 11.0 8.0 3.9 2031.1670 MAR 20.6 10.2 1.7 11.2 8.2 3.8 2031.2503 APR 23.5 11.4 2.3 11.5 8.3 3.6 2031.3337 MAY 26.6 12.8 2.5 11.7 8.5 3.4 2031.4170 JUN 31.6 14.6 3.2 11.8 8.7 3.4 2031.5003 JUL 35.4 16.6 4.4 12.0 8.8 3.4 2031.5837 AUG 39.4 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 10.4 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