HOUSTON (KIAH) — Goodbye, summer. Hello, (meteorological) fall!
The autumnal equinox, which marks the beginning of astronomical fall, isn’t scheduled to arrive until Sept. 22. But for weather and climate record-keeping purposes, the seasons are neatly divided into “meteorological” seasons of three months each — and “meteorological fall” consists of September, October and November.
NOAA’s Climate Prediction Center believes that most of the U.S. is likely to experience warmer-than-normal temperatures over the course of September, October and November.
The map below shows nearly the entire country in shades or orange, indicating NOAA’s forecast for a warm fall. The darker shades of orange around Colorado and the Northeast mean those states are the most likely to see hotter-than-average temperatures.
The rain outlook isn’t quite as clear, but favors a drier-than-normal season for a large swath of the country. Only Washington state and Florida are looking wetter than usual, while Colorado, Utah, southern Illinois, Indiana and Kentucky all have especially high chances of a dry meteorological fall.
Some of the most populated areas, along the coasts, for example, fall in the “equal chances” category. This doesn’t mean these areas will see near-normal precipitation, but rather that these areas have an equal chance of above-normal, below-normal or near-normal precipitation. Essentially, there is no clear indicator to make a confident forecast one way or another.
NOAA’s Climate Prediction Center weighs several factors into their long-range outlooks. One of those is the ongoing La Niña pattern. La Niña means the sea surface temperatures of the Pacific Ocean near the equator are cooler than normal, which impacts global weather patterns in a specific way.
The warm temperatures and potentially dry skies are an ongoing drought concern, a NOAA spokesperson told Nexstar earlier this month. La Niña lasting through the fall and winter would likely mean making a very bad drought even worse for the band of states from California to Texas, which are seeing the worst drought conditions.
The outlook for September, specifically, indicates that temperatures in a large area of the West are leaning toward warmer-than-normal. But there’s also a large area (mainly in the Southeast) in the vague “equal chances” range.
September’s precipitation outlook is even more tricky. Again, a large area falls in the “equal chances” forecast zone. Of course, in September, the wild card for the Gulf Coast states is the arrival of a tropical system. As of Wednesday, a named storm is not expected to make landfall within the next five days.
La Niña, which often has an impact on hurricane season in the Atlantic, runs through November. La Niña years typically correspond with busy and especially destructive hurricane seasons, and this year NOAA expects somewhere between three and five “major” hurricanes to form.