In general: When there is a lunar eclipse, it will always be on the 14th, 15th, or 16th of the Hebrew month. That is why it is not uncommon for a lunar eclipse to happen on Purim/Pesach/Sukkos.
As for the siman ra: I too have heard that. It would explain why we Jews have had it rough over the centuries- lunar eclipses are pretty common (and correlate with our calendar), and are quite frequently visible somewhere in the world given the right time of month.