What to expect during the final month of summer

 

An August day in the nation's capital

August will get off to a typical start this weekend with highs around 90° today and scattered showers and storms tomorrow. That's especially welcome news, since August is traditionally the second hottest month of the year and the DMV (DC, Maryland Virginia) has been mired in drought conditions. 

Average daily high/low temperatures in Washington, D.C. range from 89°/72° on August 1 to 86°/69° on August 31. D.C.’s hottest August temperature was 106° on August 6, 1918. The coolest August temperature of 49° has occurred three times, most recently on August 29, 1986.

On rare occasions, August is the warmest month of the summer. There have been four such instances over the last 20 years, most recently in 2018. Triple-digit heat is also less common in August than in July. And, there’s been 100-degree heat in only two of the last 10 August’s. Since official weather records began in 1871, the nation’s capital has seen 34 August days of triple-digit heat, down from 68 in July, but ahead of June (17) and September (4).

August is one of the drier months of the year in Washington, D.C. with NOAA’s updated rainfall average of 3.25”. There have been four August’s since 2010 that were significantly drier than average (2025, 2019, 2015, 2013). Last August even set a new record for being DC’s driest August with only 0.2” of rain.

August's stretch of near to below average temperatures will continue for much of the next week, but that will largely be a function of cloud cover with scattered showers and thunderstorms. NOAA’s Climate Prediction Center expects this month to finish with near to warmer than average temperatures combined with average rainfall in the DMV.

What is remarkable about this July’s weather?

 

A fine day in the nation's capital

July 2026 will finish as a warmer and drier than average month in the nation’s capital. This month’s weather could be summarized into two distinct halves with record-setting heat over the first half of the month. However, that was followed by stretches of mild, September-like weather. 

This month got off to an exceptionally hot start in the DMV (DC, Maryland and Virginia). DC’s hottest July 4 on record was the signature weather event. It was the third in a stretch of three consecutive days of triple-digit heat. DC’s high of 103° on Independence Day broke the old record high of 100° that had stood since 1919. Two of these days also had low temperatures that remained in the low 80s, with a third such occurrence on July 16. That’s unusual in the nation’s capital, although it has occurred more frequently in recent decades due to the impacts of climate change and a more intense urban heat island effect.

The nation’s capital has felt more like September over the final third of July. There have been no warmer than average days since July 22. Although this month will still finish as a slightly warmer than average month, the predominantly cooler than average temperatures over the final week of July will prevent it from ranking among DC’s Top 10 warmest July’s. That’s remarkable considering how hot it was to start the month.

Despite several days of showers and storms around the DMV, July will still finish with below average rainfall (3.58” vs. 4.33”). That’s significant since 18 of the last 24 months have been drier than average in the nation’s capital. This will also be our second consecutive drier than average July – something that hasn’t happened in DC since the very hot 2011-2012 summers.

The nation’s capital hasn’t had a wetter than average month since January. The drier than average weather, combined with the warmer than average weather in June and July, has exacerbated local drought conditions. The latest Drought Monitor Index shows widespread moderate to severe drought conditions exist around the DMV.

The hottest time of the year?

 

Dangerous July heat in the DMV

July is the hottest month of the year in the nation’s capital based on average temperatures kept by NOAA. The hottest days are from July 11 - 27, when average daily high/low temperatures are 90°/73°. NOAA’s climate averages are based on a 30-year dataset that’s updated every decade. NOAA updated its averages in 2021 to reflect the period from 1991-2020, which replaced the previous data set from 1981-2010.

Since the 2010s were a much warmer decade than the 1980s, DC’s average daily high temperature increased from 89° to 90° for most of the month. That should not surprise longtime Washingtonians as seven of DC’s 10 hottest July’s have occurred since 2010. Consequently, DC’s average July temperature (combining daily high and low temperatures) for the 30-year period from 1981-2010 was 79.8°, but rose to 81.0° when updated to reflect the more recent time period.

More triple-digit heat has occurred in July than any other month in the nation’s capital. All but three July days have seen triple-digit heat since official weather records began in 1871.

This month got off to a torrid stretch in the nation’s capital with a rare stretch of triple-digit heat on three consecutive days (July 2 – July 4). That was followed by two more days in the upper 90s on July 15 and July 16. Although July 2026 got off to an exceptionally hot start, it will not rank among DC’s Top 10 warmest due to the near to below average temperatures that have been prevalent during the second half of the month.

Weather observations in the nation’s capital are made at National Airport. A southerly wind at National Airport blows off the cooler waters of the Potomac River. That tends to keep the air temperature a few degrees cooler during summer than downtown areas away from the river. That doesn’t mean, however, it’s any less humid or uncomfortable.

The major takeaway is that while triple-digit heat is relatively rare in the nation’s capital, the most likely time for it to occur is in mid-to-late July given historical weather data. But triple-digit heat isn’t necessary for there to be dangerously hot conditions in the DMV (DC, Maryland and Virginia). Drinking plenty of water, doing outdoor activities early in the day when its cooler, and applying suntan lotion regularly are all good summer safety tips.