What is generally the best time for long-distance 10-meter band propagation via the F region?

The F region of the ionosphere relies heavily on ultraviolet radiation from the sun to become ionized. Because of this dependency, F-layer propagation is generally strongest during daylight hours, spanning from dawn to shortly after sunset. Furthermore, the 10-meter band sits at the higher end of the high frequency (HF) spectrum and requires a very high level of ionization to reflect signals back to Earth. This intense ionization only occurs reliably during periods of high sunspot activity, making the combination of daylight hours and a solar peak the ideal environment for 10-meter long-distance communication.