Protection of 1-wire stations
Dallas Semiconductor page has a very good description on how to do the best you can at preventing lightning and static from destroying your weather station.
How to prevent lightning/static problems
Sites with 1-wire transient protection schemes...
http://www.simat.org.uk/transprot.html
http://pond1.gladstonefamily.net:8080/surge-protection.html
Isolation methods
You can add some protection by providing isolation at the PC bus master. This can be done by usinga isolated bus master. Several 1-wire companies have such products. Another way is to build a RS-232 opto-isolator circuit or to but one commerically. A good source for a commerical unit is from: http://www.bb-elec.com/ .
Yet another is to use fiber optics or wireless. Several companies has these sorts of devices. Check the manufactures linking to see what is currently available.