(NBC NEWS) -- There have been over two dozen human cases of West Nile Virus reported this season, but those numbers pale in comparison to what we were seeing at this point last year.
A new study is giving researchers important clues for prevention.
After five years of relatively mild mosquito activity, 2012 struck the nation hard, with more than 5,000 reported cases and nearly 300 deaths.
Dallas County in Texas had the most cases.
Researchers have pored over data collected in Dallas last summer to look for patterns that could predict future outbreaks.
One thing they found is winter weather plays a large role in the summer mosquito population.
"If you don't have a good freeze it's going to, of course, set you up for more mosquitoes later," explains Dr. Kristy Murray of Baylor College of Medicine.
Keeping track of West Nile Virus in mosquitoes can predict what's likely to be transmitted to humans.
If there are lots of infected mosquitoes there will be more human cases, so experts suggest spraying for the bugs sooner rather than later. The risk from the insecticide was found to be low.
Contrary to popular belief, the heavy rain experienced by much of the country this spring and summer could be helping by washing out mosquito breeding grounds.
The key is making sure rain water doesn't collect in bird baths or flower pots where mosquitoes can multiply.
This winter started out with normal temperatures across most of the country and fell below average in March and April.
So far this season we're seeing roughly the same number of West Nile cases that were reported at this point last year. Experts at the CDC say there is no way to tell if we're in for another season that is buzzing with activity.