The weather certainly gives you at least a justification for what happened but will unlikely result in a complete defense. You have a duty to drive your vehicle in such a way that it is safe given the prevailing conditions. This means that you as a driver have to take into account the rain and other circumstances on the roadway at the time, and make adjustments for these circumstances. WIth that said, you should definitely consult with a local traffic attorney to see if they may be able to get the charge reduced or even thrown out. If you have a clean driving record otherwise, you may be able to explain to the Judge what happened and he or she may provide some leniency. I wish you the best of luck and am happy to hear that no one was injured.
The weather conditions hurt your case significantly. Bad weather means that you have to reduce your speed (possibly to way under the speed limit) and anticipate pooled water, so the case against you sounds pretty solid even looking at it in your own words.
Having said that, a ticket will increase your insurance and also cost you in fines. Prior to entering a plea, talk to an attorney to see if, based on the court your are in, the detailed facts, and other things, if that court might be receptive to a disposition with the least impact on your insurance and record.
I agree with the theme from my colleagues. I would just add that Judges have significant discretion in dealing with situations like yours, especially with statutes that use terms like "as nearly as practicable." With no other cars and no injuries, a judge may look at these facts and conclude that you've already experienced a personal cost for what happened and nothing else needs to be done. I can also see a good local traffic court attorney negotiate this situation in a very favorable way for you.
All the best.