XBeePRO comunication fails in stormy days and by night

I have 2 XBEE-PRO Modules separated by almost 100m. They are configured to comunicate in transparent mode. I used TL-ANT2405C omni 5dbi indoor antennas one in each module. I have the following problem, during the day with clear sky both modules comunicates perfect, but in the night and in stormy days the link fails. What could be hapening? I supose that the antennas have low gain and i must use higher gain outdoor omni antennas. Is this correct, can anyone help me?

Thanks a lot.

Eng. Juan Manuel Rosso
DIGIPRINT SRL

ohayougozaimasu,

Probably, the output of radio is decreasing it under the influence of rain.

2.4 GHz tends to be absorbed by moisture.

If XBee of other frequency is tried, how is it?