If she can get under something and stay dry, with wet legs you should blanket.  Blanketing a wet horse isn't your problem, the issue is what happens when the blanket gets soaked.  I treat my blankets with scotchgard so that the water runs off, any water repellent would work. 

In a pinch you can cover a blanket with a lightweight tarp or plastic trash bags if your horse will tolerate this kind of "alien attack."

Let's see, Last week it was around Zero most of the week. My horses were standing out in the snow storms. Often with 1" of snow on their back, neck and ears. As it melted it soaked their back.   They stood with water  runs running off their sides.

They have a run in shed they can go to any time they want. But they choose to stand out in the blowing snow.

So No, I don't think a horse needs a blanket if they get wet.  But wet doesn't mean cold even during cold weather.

I do think a horse needs a blanket if they are cold.  if they can not get out of the weather and get shelter, if they haven't been able to get  their normal feed, if you have clipped the horse, or been using blanket and the horse has not haired up. Then Yes, A blanket is appropriate.

Thanks everyone for your answers.. i posted that soon after getting up this morning and getting kids to school.. I hadn't been to the barn yet.. A quick call to the barn manager and, no, Eve  was not shivering, or even distressed.. She got half a bale of hay to chew through and was fine.. She HAD been through worse last year while very underweight, but it felt pretty miserable to me and I knew she was under the eves and not in a stall.. She seems to be fine.. I had read (maybe here?) something about a blanket on a wet horse kept them wet and put them at risk to be even more chilled.. The blankets I have are medium weight and turnout/waterproof.. I do have fleece underblankets, if needed, so never felt the need to get a heavy one.. Plus it is rarely cold here for very long and I don't much like to blanket anyway.. I feel that it can hurt more than help it certain situations....

Anyway.. we are OK... Thanks again for the input..

Patti, I spent a year in Wichita Falls Texas. Plus I can't tell you how many days I've spent in Dallas or Houston over the past 30 years as I've travelled there for business.  So I have some idea of what your humidity and temps are.  I guarantee you 0* with a 10 or 20 mph wind blowing ice crystals in your face is still colder than ANY humidity factor at 40*!

Yes I understand your horses don't hair up like our horses do. But they hair up enough to tolerate your climate. The animals are extremely adaptive if given enough feed.

I'm sure that if I came down to Texas and drove across your area of the state, I would see horses standing out in fields with out barns. Using only trees and fence rows for wind breaks, And that they would also be surviving the local temps. As Farmbabe said, We as humans have a tendency to think our horses are cold because we are cold. But in reality Mother Nature takes pretty good care of them. I have no problem with blanketing a horse that has been shaved, or with a horse that is aged, not getting the feed it needs for some reason, or that has been worked to a sweat. But a normal horse giving it's own free will, can probably cope with  the elements.

Here is a link to a great article about blanketing horses and how they use their hair to control their temperature.

http://www.equinesoundness.com/NewsletterMarch2009.pdf