What does "wet start" mean? Does it refers to "lousy start to begin a day"? Is it a common phrase?
"Wet start" in this scenario actually means that it rained! Since this is a weather forecast, she is telling the viewers that it rained that morning. In weather forecasts (depending on the location), this can be a common phrase. It also can be used in other weather situations. For example, I live in a cold and snowy climate. If it snowed that morning during the winter, the meteorologist would sometimes say, "We had a snowy start." or "a cold start." I believe meteorologists use these kinds of phrases to engage their audiences; to keep them interested.