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% 2025.1670 MAR 143.4 136.8 131.6 16.1 14.8 13.3 2025.2503 APR 145.0 134.4 122.8 17.2 15.0 12.8 2025.3337 MAY 145.6 132.6 119.0 18.0 15.1 12.7 2025.4170 JUN 150.6 130.8 115.0 18.8 15.1 11.9 2025.5003 JUL 151.4 128.2 108.2 19.5 15.1 11.1 2025.5837 AUG 151.7 125.5 101.5 20.4 15.1 10.9 2025.6670 SEP 154.9 123.3 96.0 21.0 15.4 10.5 2025.7503 OCT 157.0 121.5 91.9 21.6 15.7 10.1 2025.8337 NOV 159.2 119.3 87.5 21.7 15.9 10.4 2025.9170 DEC 162.4 116.6 81.8 21.2 16.1 10.9 2026.0003 JAN 163.7 114.0 75.6 20.3 16.1 11.0 2026.0837 FEB 160.7 111.7 72.0 20.3 16.1 11.0 2026.1670 MAR 156.7 109.9 70.9 20.5 16.1 11.5 2026.2503 APR 154.1 108.2 70.5 20.9 16.1 11.9 2026.3337 MAY 151.8 106.4 70.0 21.5 16.2 11.9 2026.4170 JUN 148.2 104.2 68.4 21.7 16.4 11.8 2026.5003 JUL 143.9 101.5 65.8 21.2 16.4 12.1 2026.5837 AUG 135.6 98.8 62.5 20.7 16.3 12.7 2026.6670 SEP 134.1 95.8 59.4 21.6 16.2 12.9 2026.7503 OCT 133.4 92.6 56.3 22.0 16.0 12.9 2026.8337 NOV 131.7 89.8 52.2 21.9 16.0 12.5 2026.9170 DEC 127.6 87.0 50.0 22.1 16.0 12.2 2027.0003 JAN 123.4 84.5 48.2 22.5 16.1 12.1 2027.0837 FEB 121.5 82.4 46.1 22.3 16.1 12.2 2027.1670 MAR 121.9 79.9 42.7 22.3 15.9 11.7 2027.2503 APR 122.5 77.3 37.4 22.6 15.7 11.5 2027.3337 MAY 122.9 74.9 33.3 22.8 15.4 11.0 2027.4170 JUN 122.5 72.6 30.7 23.4 15.2 10.1 2027.5003 JUL 119.9 70.0 27.8 24.0 14.9 9.4 2027.5837 AUG 118.6 67.5 24.8 24.7 14.8 9.4 2027.6670 SEP 116.3 65.3 22.9 25.2 14.7 9.4 2027.7503 OCT 111.9 63.3 22.0 25.4 14.7 9.4 2027.8337 NOV 108.4 61.3 21.1 25.3 14.5 9.6 2027.9170 DEC 105.8 59.0 19.3 24.8 14.4 9.8 2028.0003 JAN 104.8 56.9 17.4 23.9 14.2 9.8 2028.0837 FEB 103.8 55.2 16.0 23.0 14.1 9.2 2028.1670 MAR 101.5 53.3 15.6 22.5 14.1 8.7 2028.2503 APR 98.2 51.3 15.9 22.1 14.2 8.0 2028.3337 MAY 94.0 49.1 15.9 21.8 14.3 7.4 2028.4170 JUN 90.3 47.3 15.2 21.4 14.4 7.3 2028.5003 JUL 89.0 45.9 14.4 20.8 14.4 7.7 2028.5837 AUG 87.2 44.3 14.7 19.9 14.2 8.1 2028.6670 SEP 84.5 42.4 15.3 20.1 14.1 8.4 2028.7503 OCT 80.5 40.3 14.3 20.3 13.9 8.4 2028.8337 NOV 76.7 39.0 13.5 20.0 13.7 8.4 2028.9170 DEC 74.3 37.8 14.8 19.6 13.6 8.3 2029.0003 JAN 70.8 36.1 15.5 19.0 13.6 8.3 2029.0837 FEB 66.2 34.5 14.5 18.3 13.6 8.4 2029.1670 MAR 63.5 32.8 13.4 17.4 13.5 8.1 2029.2503 APR 62.0 31.3 12.1 17.5 13.3 7.8 2029.3337 MAY 60.1 29.7 11.3 17.6 13.1 7.7 2029.4170 JUN 58.2 28.2 11.1 17.8 13.0 7.7 2029.5003 JUL 56.4 26.9 10.2 17.8 12.9 7.2 2029.5837 AUG 54.2 25.6 9.0 17.8 12.8 7.0 2029.6670 SEP 51.9 24.1 7.6 17.8 12.7 7.2 2029.7503 OCT 48.8 22.7 6.4 17.8 12.5 6.9 2029.8337 NOV 44.3 21.5 6.7 17.5 12.3 6.8 2029.9170 DEC 40.5 19.9 6.4 17.2 12.0 6.6 2030.0003 JAN 37.5 18.2 5.3 16.2 11.6 6.5 2030.0837 FEB 34.6 16.6 4.3 14.8 11.2 6.4 2030.1670 MAR 33.8 15.2 3.5 13.9 10.9 6.3 2030.2503 APR 33.2 14.2 3.1 14.0 10.5 6.3 2030.3337 MAY 32.4 13.2 3.2 13.7 10.2 6.3 2030.4170 JUN 31.5 12.4 3.2 13.2 9.8 6.1 2030.5003 JUL 28.9 11.6 2.7 12.9 9.5 5.9 2030.5837 AUG 25.7 10.8 2.4 12.6 9.3 5.8 2030.6670 SEP 23.6 10.0 1.7 11.9 9.1 5.7 2030.7503 OCT 22.1 9.3 1.1 11.4 8.9 5.2 2030.8337 NOV 20.3 8.6 1.0 11.3 8.7 4.9 2030.9170 DEC 20.1 8.7 0.9 11.2 8.7 4.9 2031.0003 JAN 20.9 9.4 1.5 11.4 8.7 4.6 2031.0837 FEB 22.6 10.5 2.0 11.7 8.9 4.6 2031.1670 MAR 24.2 11.7 2.3 11.8 9.0 4.5 2031.2503 APR 26.7 12.7 2.9 12.0 9.0 4.2 2031.3337 MAY 29.4 13.9 3.0 12.1 9.1 3.9 2031.4170 JUN 33.8 15.6 3.6 12.2 9.2 3.8 2031.5003 JUL 37.2 17.3 4.7 12.3 9.2 3.7 2031.5837 AUG 40.8 19.2 5.2 12.6 9.4 3.6 2031.6670 SEP 46.1 21.4 5.8 12.9 9.7 3.5 2031.7503 OCT 52.9 23.7 6.2 13.3 10.0 3.8 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 176.8 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 231.1 127.1 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 241.6 141.1 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 260.5 150.2 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 75.8 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 163.9 109.2 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 115.8 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 98.2 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 13.5 22.1 14.2 8.1 2039.3337 MAY 86.4 51.3 13.6 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