Final answer:
The provided text is not a run-on sentence; it's a fragment missing a subject. Adding a subject would make it a complete sentence, commonly seen in weather forecasts discussing temperatures and storm chances.
Step-by-step explanation:
The sentence you've provided, "can expect warmer temperatures and partly cloudy skies, with a chance of thunderstorms," does not qualify as a run-on sentence because it isn't actually a complete sentence. It's lacking a subject, which is necessary for a sentence to be complete. This part of text looks like a fragment from a weather forecast that could follow a subject, such as "You" or "We," to make a complete sentence.
Weather forecasts typically include information about expected temperatures, cloud cover, and the chance of precipitation, like rain or thunderstorms. In reports about future precipitation and storm events, such language is common where changes in weather patterns are described, including variations in temperatures and the likelihood of different types of weather conditions.