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NVIS Optimum  HF Frequencies (foF2)
for communications within 300 kilometers
To use these 4 maps, locate the map for your location and click on it. 
The color (frequency) at your location is the optimum frequency for F2 layer NVIS communication.
Updated at 40 minutes past the hour; Click on the maps to zoom and reload.
NORTH AMERICA
Click: Real Time HF Propagation		 EUROPE
Click: Real Time HF Propagation		 Aust-NZ 
Click: Real Time HF Propagation		 Far East Asia 
Click: Real Time HF Propagation
NVIS for North America - Atlantic - Europe
NVIS North America to Europe

 

Wide Region Optimum HF Frequencies
for Distant Communications, Centered on World Cities
To use these longer distance maps below, locate a map for the city nearest your location and click on it. 
Locate the distant point on the map for communication with. 
The color at that distant location point determines the best frequency to use.
Updated at 40 minutes past the hour; Click on the maps to zoom and reload.

San Francisco

Click: San Francisco Zoom

 Boulder
Boulder Zoom		 Kansas City
Kansas City Zoom		 Washington DC
Washington DC Zoom
Whitehorse
Whitehorse Zoom		 Montreal
Montreal Zoom		 London
London Zoom		 Rome
Rome Zoom

Stockholm

Stockholm Zoom

Tokyo

Tokyo Zoom

Sydney

Sydney Zoom

Darwin

Darwin Zoom

Perth

Perth Zooom

Auckland

Auckland Zoom

Australia/NZ regional maps frequency color bar

 

These maps are made from data gathered in real time around the world using HF ionospheric radar systems called ionosondes. Ionosondes bounce HF radio signals off the ionosphere to measure the height of the reflective zones and signal strength vs frequency. The maps are generated using the ionosonde data to make projections based upon a base station communicating with a mobile. Mapping source: Australian Government IPS Radio and Space Services
Shortwave Fade-Out Chart
 If this map is in Black and White, there is no ShortWave Fadeout (SWF).
It will show colors only during an SWF event.
Chart TIME:------SWF Status:                              
Shortwave Fade-Out Chart
 

During a solar flare, increased ionisation in the D-layer of the ionosphere can result in reduced signal strengths for HF circuits which are reflected by the ionosphere on the sunlit hemisphere of the earth. This is known as a short-wave fadeout.

The map above shows the absorption limited frequency (ALF) - the lowest frequency able to propagate - for HF circuits typically 1500 km in length. To use the plot, work out the approximate location where your circuit is being reflected by the ionosphere and estimate the value of the ALF from the contours. If the frequency you wish to use is lower than this value then communication is unlikely; if it is higher than the ALF then communication is still possible.

For short circuits compared with 1500 km, the ALF values from the map are likely to be too high and communications will still be possible for slightly lower frequencies. For much longer circuits, slightly higher frequencies than the suggested ALF can still be affected by the fadeout.
 

GOES Xray Flux
 These plots are updated every five minutes using X-ray information supplied by the US Space Environment Center. A plot of solar X-ray flux for the last three days is provided in Today's Space Weather by Space Environment Center in Boulder.