A distinct La Niña system building in the Pacific and pattern of troughs and ridges in northern North America translates to cooler temperatures starting next week, but a noticeable lack of rainfall for the western Corn Belt and Plains, enabling farmers to make good progress on fall harvest. Sinking temperatures do create some concerns about frost in the eastern Corn Belt where chances are greater for rainfall through the next week or so, and La Niña makes warm, dry conditions likely for much of the western U.S., adding to wildfire concerns in that part of the country. Based on current models, these conditions are likely to remain intact through at least the first half of October. See more from the latest long-term weather outlook here.