This is a monthly trend chart compiled using the monthly average Solar Flux numbers.

Click HERE to compare the average Flux to the Cycle 24 predictions.

Complete History of Monthly Averages from 1991 to Current can be found at http://www.swpc.noaa.gov/ftpdir/weekly/RecentIndices.txt

Month
High
Low
AVG
July 08
67
65
65.8
June 08
67
65
65.9
May 08
72
66
68.4
Apr 08
78
67
70.3
Mar 08
89
68
72.9
Feb 08
73
70
71.2
Jan 08
80
70
72.1
Dec 07
94
71
78.6
Nov 07
72
67
69.7
Oct 07
69
66
67.5
Sept 07
71
65
67.1
Aug 07
72
67
69.2
July 07
79
66
71.6
June 07
87
65
73.7
May 07
87
67
74.5
Apr 07
87
68
72.4
Mar 07
76
69
72.3
Feb 07
90
73
77.8
Jan 07
92
76
83.5
Dec 06
103
72
84.3
Nov 06
97
77
86.4
Oct 06
80
70
74.3
Sept 06
87
70
77.8
Aug 06
89
70
79.0
July 06
88
70
75.8
June 06
86
72
80.1
May 06
93
72
81.0
Apr 06
101
74
89.0
Mar 06
86
72
75.5

* Graph plot boxes from 0-100 are in intervals of 5, above 100 in intervals of 10.
* The white markers indicate the maximum Solar Flux of the month.

Solar Flux Definition

The 10.7 cm (2800 MHz) radio flux is the amount of solar noise (light) that is emitted by the sun at 10.7 cm wavelengths. The solar flux is measured and reported at approximately 1700 UT daily by the Penticton Radio Observatory in British Columbia, Canada. Values are not corrected for variations resulting from the eccentric orbit of the Earth around the Sun.

The solar flux is used as a basic indicator of solar activity. It can vary from values below 50 to values in excess of 300 (representing very low solar activity and high to very high solar activity respectively). Values in excess of 200 occur typical during the peak of the solar cycles.

The solar flux is closely related to the amount of ionization taking place at F2 layer heights (heights sensitive to long-distance radio communication). High solar flux values generally provide good ionization for long-distance communications at higher than normal frequencies. Low solar flux values can restrict the band of frequencies which are usable for long distance communications. The solar flux is measured in "solar flux units" (s.f.u.). One s.f.u. is equivalent to 10^-22 Wm^-2 Hz^-1.