WRAL WeatherCenter Blog

Fall makes a comeback this weekend

Posted October 15, 2021 10:29 a.m. EDT

Highs have been well above normal for much of this week, but that’s about to change. A cold front will cross the area on Saturday and deliver some much cooler, drier air.

Fall cold front

We have lows in the 40s in the forecast for Monday morning! There may even be a few spots that drop into the upper 30s for the first time since last spring.

Cool mornings ahead

Our normal low for this time of year is 51, but we are getting close to our first average freeze date. The average freeze date for RDU is the first week of November.

The earliest 32-degree temperature at RDU in the fall is Oct. 2, 1947 and the latest is December 3, 1931. Our warming climate means those first frosts are coming later than they used to.

First frost arrives later

Of course, the fall is the end of the growing season and whether you’re a farmer or a backyard gardener, you want to know when it’s time to put the garden to bed for the winter.   

The National Weather Service may issue one of several advisories when our temperatures are forecasted to fall near or below freezing in the fall:

Frost Advisory: A frost advisory is issued when temperatures are forecast to be in the 33°F to 36°F range with good radiation conditions. Typically, frost can occur when the temperature falls below 36°F, especially in rural areas. It is a localized phenomena and can be quite variable across a small area.

Freeze Warning/Watch: A freeze warning is issued when minimum temperatures are forecast to be 32°F or less.  Frost becomes more widespread when the temperature falls below 32°F with some freeze possible. A Freeze Watch may be issued a few days ahead of time if the potential exists for temperatures to fall into these thresholds.

Hard Freeze Warning/Watch: A hard freeze warning is issued when temperatures are expected to be 28°F or less. A Hard Freeze Watch may be issued a few days ahead of time if the potential exists for temperatures to fall into these thresholds.

Once an area reaches freezing, the NWS no longer issues the advisories because it’s understood that the growing season has ended and more freezing temperatures are on the way until spring.

As our climate warms, we see these freezing temperatures coming later in the fall and ending earlier in the spring.   This is true across the country. 

Longer growing season

According to the EPA, the growing season is two weeks longer now than it was 100 years ago. There are benefits to that. Farmers can grow food longer and days with dangerous winter conditions are fewer. There are downsides too.    The allergy season is longer and we see more days with mosquitoes and ticks.  

For now we have some cool fall weather in our forecast. I’m looking forward to throwing on a sweater!   

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