Space weather, week 35 of 2026.
·Week 35 of 2026, August 24, 2026 to August 30, 2026, 3 of 7 days recorded. No day reached storm level; the most disturbed day was August 28, 2026, with the Kp index (0 to 9, storm at 5 and above) peaking at 4.3, active conditions, no storm. The Sun let off 4 small (C-class) flares over the week. The daily sunspot count ran from 73 to 92, averaging 80, a moderately active Sun.
One section per complete UTC day, written by the daily data run from NOAA's feeds: the planetary Kp index every three hours, the GOES X-ray flare list, NOAA's daily sunspot number and 10.7 cm flux, and hourly solar wind at L1. Nothing here is edited by hand. The record index explains each figure, and the same numbers are in the open data file.
Friday, August 28, 2026
Earth's magnetic field was active conditions, no storm: the Kp index, a 0 to 9 scale where 5 and above counts as a geomagnetic storm, peaked at 4.3 in the 18:00 to 21:00 UTC window and averaged 2.5 for the day. Aurora reached only the far north, Alaska, northern Canada, and northern Scandinavia. The Sun produced no flares worth recording (nothing reached C class, the smallest size NOAA lists). NOAA's sunspot count was 92, a moderately active Sun (0 is no spots at all; 150 to 200 is typical at the peak of a cycle); 1 new sunspot group appeared. The Sun's radio output, a second gauge of its activity that does not depend on counting spots, read 116, moderate (about 70 for a quiet Sun, 200 or more for a very active one).
Kp through the day, one value per three hours from midnight UTC: 1, 0.7, 1, 1.7, 3.7, 3.3, 4.3, 4.3.
Saturday, August 29, 2026
Earth's magnetic field was active conditions, no storm: the Kp index, a 0 to 9 scale where 5 and above counts as a geomagnetic storm, peaked at 4.3 in the 00:00 to 03:00 UTC window and averaged 3.1 for the day. Aurora reached only the far north, Alaska, northern Canada, and northern Scandinavia. The Sun let off 2 small (C-class) flares; the biggest was C1.1 at 12:11 UTC, too small to notice on Earth. NOAA's sunspot count was 73, a moderately active Sun (0 is no spots at all; 150 to 200 is typical at the peak of a cycle); no new sunspot groups appeared. The Sun's radio output, a second gauge of its activity that does not depend on counting spots, read 111, moderate (about 70 for a quiet Sun, 200 or more for a very active one).
Kp through the day, one value per three hours from midnight UTC: 4.3, 3.3, 3.7, 3, 2.3, 2.3, 3.7, 2.
Sunday, August 30, 2026
Earth's magnetic field was unsettled: the Kp index, a 0 to 9 scale where 5 and above counts as a geomagnetic storm, peaked at 3.7 in the 00:00 to 03:00 UTC window and averaged 2.9 for the day. Aurora stayed up near the poles. The Sun let off 2 small (C-class) flares; the biggest was C3.0 at 01:20 UTC, too small to notice on Earth. NOAA's sunspot count was 74, a moderately active Sun (0 is no spots at all; 150 to 200 is typical at the peak of a cycle); no new sunspot groups appeared. The Sun's radio output, a second gauge of its activity that does not depend on counting spots, read 107, moderate (about 70 for a quiet Sun, 200 or more for a very active one).
Kp through the day, one value per three hours from midnight UTC: 3.7, 3.7, 3.3, 3.7, 2, 2.7, 2, 2.
What do these numbers mean?
Four things are tracked each day. The Kp index says how disturbed Earth's magnetic field was, on a 0 to 9 scale measured every three hours; 5 and above is a geomagnetic storm, and the higher it goes the farther south the aurora reaches. Flares are sudden flashes on the Sun, sorted by size: C-class is small and harmless, M-class is medium and can briefly fade shortwave radio, X-class is large. The sunspot count is NOAA's daily tally of dark spots, weighted so that groups count more than lone spots; it runs from 0 on a blank Sun to 150 or more near the peak of a solar cycle. The radio output is the Sun's brightness at a 10.7 cm radio wavelength, a second activity gauge that does not depend on counting spots; 70 is quiet, 200 very active. The solar wind is the stream of particles flowing past Earth, measured about 1.5 million km upstream; its speed and the north-south direction of its magnetic field (Bz) decide whether a storm follows, because a southward field lets the wind's energy into Earth's field.