Space Weather

Latest Solar Indicies:

Current Solar Flux Index (50-350)


Current K Index (0-9)


Current A Index (0-400)


Current Number Of Sunspots


10-Day Sunspot Average


Note: Solar data retrieved from Space Weather Prediction Center (NOAA) Another Note: The PHP script which gathers this data is free to download. Please note that it may have a few bugs, but seems to work most of the time.

The earth is shielded from the sun's harmful radiation by the ionosphere. The ionosphere has the ability to reflect radio waves if conditions are right. Amateur radio operators use this ability to bounce radio waves around the world. There are several pieces of information that help amateurs determine how the ionosphere will behave at a given moment. The most common ones are listed above and are all less than 24 hours old.

Ham Radio operators, shortwave radio enthusiasts often talk about propagation index numbers, the status of the solar cycle and geomagnetic conditions. Why? What do the numbers mean? On many ham radio frequencies, especially on HF, these factors determine whether worldwide contacts can be made with very little effort (low power and a modest antenna) or radio blackout conditions exist (no contacts possible). The previously listed information, adapted from NOAA, can be helpful when making predictions about radio wave propogation.

Solar flux is a measurement of the intensity of solar radio emissions with a wavelength of 10.7 cm (a frequency of about 2800 MHz. The daily solar flux measurement is recorded at 2000 UTC by the Dominion Radio Astrophysical Observatory of the Canadian National Research Council located at Penticton, B.C., Canada. The value broadcast is in solar flux units that range from a theoretical minimum of about 50 to numbers larger than 300. During the early part of the 11-year sunspot cycle, the flux numbers are low; but they rise and fall as the cycle proceeds. The numbers will remain high for extended periods around sunspot maximum.

Solar Flux Approximate Maximum Usable Frequencie (Day)
50 - 70 7MHz (40 Meters)
70 - 90 14MHz (20 Meters)
90 - 120 21MHz (15 Meters)
120 - 150 28 MHz (10 Meters)
150 - 200 45 MHz (Some openings on 6 Meters)
> 200 50+ MHz (All HF bands provide reliable comunications)

The A and K indices are a measurement of the behavior of the magnetic field in and around the Earth. The K index uses a scale from 0 to 9 to measure the change in the horizontal component of the geomagnetic field. A new K index is determined and added to the broadcast every 3 hours based on magnetometer measurements made at the Table Mountain Observatory, north of Boulder, Colorado, or an alternate middle latitude observatory. The A index is a daily value on a scale from 0 to 400 to express the range of disturbance of the geomagnetic field. It is obtained by converting and averaging the eight, 3-hour K index values.

Space Weather describes the conditions in space that affect earth and its technological systems. Space weather is a consequence of the behavior of the sun, the nature of Earth’s magnetic field and atmosphere, and our location in the solar system

This Map shows the MUF at a given location when used in a NVIS situation. Normal HF skip operations will tolerate higher frequencies than those shown. The smaller the angle of incidence the higher the MUF will be.