Second false fall for RVA
But hot and humid to finish August
3pm, August 28, 2024
The Short Version
Staying humid this coming holiday weekend, but the heat eases back between Thursday and Sunday. More clouds in the mix through Sunday with scattered showers and thunderstorms each day, and Friday brings the best chance of getting 2-3 hours worth of rain. Another false fall dominates for the few days that follow Labor Day, and we might be done with 90s for the year after that.
Full Story: Peak of the heat
The intense heat from Wednesday will progressively wane from Thursday through the weekend. In fact, Wednesday just might be the last day above 95 for the rest of the year.
Thursday backs toward the lower 90s, and Friday holds in the 80s with more clouds. Both days bring a chance of showers and thunderstorms, although the chance is a little lower Thursday (40%) compared to Friday (70%).
Saturday and Sunday will be in the upper 80s, and the chance for a couple of showers or thunderstorms stubbornly remains at about 40% each day.
Plus… the humidity will remain high through Sunday.
False Fall, Part II
A cooler airmass will move into Virginia on Labor Day, suggesting a holiday with no rain in Richmond, a gradual drop in humidity, and an afternoon temperature in the lower 80s. This also marks a transition to another false fall in Richmond, similar to last week — with afternoons in the upper 70s to around 80 and lows tumbling to around 60 from Tuesday to Friday next week.
Two stats emphasize the rarity of last week’s false fall.
First, the five nights in the 50s last week marked the most August nights below 60 in Richmond since 1998 (six that year).
Second, August 21 was the first day in the last 4 months that was at least 10 degrees cooler than normal. During that same period, Richmond had 8 days at least 10 degrees warmer than normal.
This weekend will also close the book on meteorological summer (i.e. the three warmest calendar months of the year) in Richmond. Depending on precisely how hot the next few days are, this summer will fall between the 3rd and 5th hottest since daily record temperatures in Richmond began in 1897.
September Outlook
Despite the cool start to month, preliminary data suggest a flip back to conditions warmer than normal for the second half of September. The end result may be a September that doesn’t cool as consistently as we might expect, yet still ends up within a degree or so of normal.
For perspective, normal high/low temperatures at the start of September are 85/65. At the end of the month, they are 76/56.
With this in mind, it is tempting to suggest that we will be finished with days in the 90s after Labor Day.
Looking back over the last 10 years, Richmond averages 6 days in the 90s in September, with only 2 of those 90+ days coming in the second half of the month. Even if we are not entirely done with 90s after Labor Day, the number of September days in the 90s will almost certainly be below average.
Enjoy the break while we have it. Fall is getting warmer.
Regarding rain, and unlike our friends in the Shenandoah Valley, Richmond has recovered well from the dry June — with total summer rainfall now hovering at 9 percent above normal. The first half of September favors rain near normal, then less than normal for the second half of the month.
Normal September rain in Richmond is 4.61 inches — roughly about an inch a week.
Tropics? What Tropics?
While the tropics remain quiet for the moment, expect them to bubble back to life after Labor Day. There is no way to know if Virginia will get something from the tropics before the peak of the season ends in October, but for the next couple of weeks, the highway from the tropics into Virginia appears to be closed.