This is generating about 200MB of logfile an hour.

Here's the line of code doing it:

Maybe only log it every 500 ticks or so, if needed for debugging.

if (wi.getRainTime() % 500 == 0) {
    Hydrophobia.LOGGER.info(wi.getRainTime());
}

I concur, seeing this with 1.0.4. as part of towncraft mod pack.

This also makes the server console unusable.

Oops, left a debug line in. Fix incoming, and sorry for the mess ;)

Update pushed to curseforge.