The first day of autumn — Sept. 22 this year — is no guarantee of fall-like weather, but officially the season’s start comes around at the same time each year nonetheless.

The first day of autumn arrives on varying dates in different years for two reasons: Our year is not exactly an even number of days; and Earth’s slightly noncircular orbit, plus the gravitational tug of the other planets, constantly changes our planet’s orientation to the sun from year to year.

And weather-wise, Earth’s seasons have shifted in the past 150 years or so, according to a study that came out earlier this year. The hottest and coldest days of the years now are occurring almost two days earlier.

This year, fall starts Tuesday, because that is when the so-called autumnal equinox occurs (at 5:18 p.m. EDT). Equinoxes (which mark the onset of spring and autumn) and solstices (which mark when summer and winter begin) are points in time and space that mark a transition in our planet’s annual trip around the sun.

At each equinox, the sun crosses the Earth’s equator, making night and day of approximately equal length on most of the planet (from the Latin, equinox means “equal night”). At the equator, the sun is directly overhead at noon on either equinox.

Source: LiveScience.com

Here come our cold front...

Tuesday marks the beginning of Fall but technically speaking, it does not begin until 4:18 PM. I bet by that time, it will feel like Fall with much cooler temperatures, cloudy skies, and even a few linger showers. All of this will be thanks to our cold front that will move through early on Tuesday morning and continue heading towards the Texas coast by the evening. Right now, we are anticipating a line of showers and storms to develop along the front and back build southward into Central Texas. There is a slight risk for severe weather with strong winds, lightning, and heavy rain the main threats. In fact, we already have a Flash Flood Watch in effect for the northern counties. Behind the front, north winds will usher in cooler air, which will lead to lows in the 60s and highs near 80 degrees.

Later in the week, the cold front is expected to lift back north as a warm front, which will bring back thunderstorm chances Thursday and Friday. Temperatures will also start warming back up by the weekend so enjoy the cooler weather while it last. The overall weather pattern is changing across the country so I would guess we will start seeing cold front on a regular basis now. — First Alert 25 Meteorologist Conley Isom

Courtesy of the NWS in Fort Worth

The weather has been nice and cool this week thanks to the clouds, rain, and a north wind. Over the weekend, that will change with a little more sun and highs near 90 degrees. Then, by early next week, we are tracking a strong storm system that will develop across the Central Plains and drive a cold front through the area. The timing is still questionable, but current data suggest the front moving through overnight Monday into Tuesday morning. This cold front will have some bite to it! First, a strong to severe line of storms is expected to develop ahead of the front. The fall season is considered our second severe weather season because of the clashing of cold and warm air. Right now, the main threats would be strong winds over 60 mph, lightning, and large hail. Of course we will update the severe weather threat as we get closer to the event. As for temperatures behind the front, keep in mind this cold front is not arctic but we do expect temperatures to cool about 10-15 degrees. This means highs near 80 degrees and overnight lows near 60s. Just to our north, we could even see temps in the 50s! All of this will happen right on cue with the first day of Fall beginning on Tuesday! — First Alert 25 Meteorologist Conley Isom

As of Sept. 17th

The latest U.S. drought monitor data has been released and like expected, the rain from last weekend really put a big dent in the Texas drought. The map above shows that the southern parts of Central Texas that were dealing with extreme and exceptional droughts, are now downgraded to moderate and severe conditions. So yes the drought does continue but it is not nearly as bad as it was. South Texas and the Hill country also saw the benefit of the rain as the deep maroon colors (exceptional drought) have shrunk. I mentioned this on air before that it will take several rain events like this past one to completely get rid of drought conditions across the area. Since it looks like hurricanes this season will stay away from Texas, we will have to rely on a wet fall and winter. And if you have been reading the Weather Blog, you would know that is what is in the forecast, thanks to the El Nino we are in. — First Alert 25 Meteorologist Conley Isom

The drought was getting worse across parts of Central Texas until this past rain event. Unfortunately, some places saw too much rain in a short amount of time which lead to the flooding we saw in Salado on Friday. There were also reports of flooding in Milam and Navarro counties on Saturday and Sunday. The image above is from the Central Texas radar site in Granger showing rainfall totals over the past 7 days. The green indicates totals of 2-3 inches, the red is totals over 6 inches, and the purples are areas that had over 10 inches of rain. The drought update will come out later this week and I am sure we will see drastic improvements. We may be in store for more of the wet stuff as we enter the fall and winter seasons. The forecast calls for the El Nino weather pattern to continue into next year, which tends to lead to cooler and wetter conditions for Texas. — First Alert 25 Meteorologist Conley Isom

Below are some more pics from of the flooding from Friday in Salado. Thanks to Joyce Pennington for sending these in to weatherpics@kxxv.com.

Rainfall totals since Wednesday

Flooding continues to be a concern across parts of Central Texas. The hardest hit areas have been southern Bell county near Salado and in parts of Williamson county around Florence and Georgetown. This is the area that has seen over a foot of rain since midweek! More rain is in the forecast through at least Monday, so more flooding is likely, especially near creeks and rivers. Please be very careful if you plan to travel in the rain. If you are heading south towards Austin, check ahead before leaving. Remember, never cross a road that has water running over it! Below are some photos we have received of the flooding in Salado. Feel free to email us your photos to weatherpics@kxxv.com. — First Alert 25 Meteorologist Conley Isom

From Adam Cuker

Main Street over Salado Creek

Rain, rain, and more rain.

There are several features that will keep our rain chances in the forecast through the weekend. First, there is a weak cold front that will slowly ease into the area on Saturday. Second, there is an area of low pressure that will be off the Texas coast. Still too early to tell if this low pressure will become something tropical but we are watching it closely(Read the post below for more info). The main effect from this system will be a surge of tropical moisture that will move into the eastern parts of the area. Combine that with the cold front and widespread rain looks likely. Some of it could be heavy with isolated amounts of 1-3 inches. Overall, no severe weather is expected but there could be some gusty winds and lightning within the stronger storms. So if you have outdoor plans for the weekend, have the rain gear ready to go! — First Alert 25 Meteorologist Conley Isom

Hurricane Fred in the Atlantic

Fred has gone through rapid intensification overnight and is now a category two hurricane way out in the Atlantic. Winds this morning are up to 105 mph and the eye is easily seen on satellite imagery. The forecast for Fred has not changed, with the storm turning northward and stay far away from any land masses. Fred should also begin to weaken as it pushes into cooler waters and runs into more wind shear which will tear the storm apart. You can track Hurricane Fred by checking out our Tropical Tracker.

Computer model showing something in the Gulf of Mexico by late Friday.

The rest of the tropics are quiet but we may need to watch the Gulf of Mexico closely over the next few days. Computer models are trying to develop an area of low pressure just off the Texas coast by Friday afternoon. Hard to tell if this will be a warm or cold core low pressure system which means if it is warm core, it would be tropical in nature. If it was cold core, it would be like our normal storm systems that move across the country. Since is it September, the heart of hurricane season, anything is possible. A good example of something like this happening in the past is Hurricane Humberto in 2007. It went from nothing to a hurricane in record breaking time, becoming the fastest intensification of any tropical system before making landfall. We will be tracking closely and will have updates through the week. — First Alert 25 Meteorologist Conley Isom