As the sunspot numbers go down, the higher frequencies become less reliable. The 20m - 14MHz band - is open usually only during daylight hours. But at the same time, the lower frequencies get better at night than they are during sunspot maxima.
When the sunspot numbers are high again, the 28MHz ham band will be "magic." You'll hear the whole world all day long and many of those stations will be using very low power and small antennas. 20m will be open to somewhere in the world 24 hours per day, but the lower frequencies will be somewhat less exciting at night.
So there's always something somewhere to hear. Part of the fun is looking for and finding it.