Weather forecasts have long been considered a special type of local/regional news, featured in newspapers and TV news for decades and continuing onto the current era where many news and news aggregation sites will have a weather section or widget.
Weather is frequently looked up information for many, with both direct and indirect effects. Expected severe weather can be especially important to know about.
Rather than going to a different site for weather, someone on Kagi news could simply look at the Weather tab. In contrast, many weather-focused sites have poor UI or are heavily ad-laden.