Just because there is snow on the ground and temps are below freezing doesn't necessarily mean the trails are frozen yet... I checked Illiniwek yesterday and there were still areas of exposed trail that were muddy (and evidence some riders haven't been following the trail closures). I imagine conditions are similar at other local trails. The trails will probably remain closed through the weekend with the warming temps. :-( Once we get a good hard freeze they should reopen and stay that way for a few months.

For more info on why the trails sometimes close during the transition to/from winter see: The Freeze/Thaw Cycle