Jakai Tunstall, 6, passes through a cascade of water as children play in the fountains at Yards Park in July 2017. (Jahi Chikwendiu/The Washington Post)

Hazy, hot and humid. They’re the dreaded three h’s, and they’re headed to Washington for the first time this year Sunday through Tuesday.

On Monday and maybe Tuesday, we expect the hottest weather of 2018 so far as temperatures shoot up well into the 90s, high enough that records could fall. Factoring in humidity, it is likely to feel like 100 degrees or higher.

The National Weather Service wrote that Monday, in particular, “could be quite an oppressive day.”

Temperatures could hit at least 90 on Sunday, Monday and Tuesday, which would meet the criteria of a heat wave, the second of 2018. The first heat wave occurred May 2 through 4, but the highs were just 91, 90 and 90, and humidity levels remained in check, with dew points in the 50s to near 60.


(The Washington Post)

For the upcoming heat wave, both temperatures and humidity levels should be substantially higher. Temperatures may peak in the upper 90s as dew points reach the 70s.

As this will be the first spell of legitimately hot weather of the season, it will be important to stay hydrated and avoid overexertion.

Let’s break down the forecast day by day …

Sunday


NAM model forecast highs for Sunday.
  • Forecast highs: 88 to 93, feels like up to 95
  • Humidity: Moderate to high, dew points 65 to 70

Father’s Day will be a good one to stay close to a body of water. It’s reasonably likely that Washington will hit 90, and humidity levels will be noticeably higher than previous days.

Dulles could even challenge the record high of 92 for the date, while the others should be safe. They are:

  • Washington: 97 from 2014
  • Dulles: 92 from 1994
  • Baltimore: 96 from 1939

Monday


American model forecast high Monday.
  • Forecast highs: 94 to 99, feels like up to 105
  • Humidity: High, dew points in low 70s

This may be the peak day of the heat wave, with highs likely to reach the mid-to-upper 90s. Factoring in humidity, it will feel like 100 to 105 degrees.

Existing high temperature records could fall at all three observing locations. They are:

  • Washington: 97 from 1944
  • Dulles: 94 from 2007
  • Baltimore: 97 from 1957

It’s also not out of the question that minimum temperatures could be at record high levels, given forecast lows in the muggy mid-70s.

Tuesday


European model high temperature forecast for Tuesday. (StormVistaWxModels.com)
  • Forecast highs: 93 to 98, feels like up to 105
  • Humidity: High, dew points in low 70s

An approaching cold front probably makes this the last day of sweltering heat. Models mostly suggest that it will be a hair cooler than Monday, but oftentimes we’ve seen the last day of a heat wave end up being just as hot as the penultimate day, if not hotter.

Note that our forecast confidence slips a little by Tuesday, it still being six days away. If the cold front speeds up, it may not get so hot.

Records on this day will be a little more difficult to top because they are higher than the previous days. They are:

  • Washington: 99 from 1994
  • Dulles: 98 from 1994
  • Baltimore: 99 from 1994

We’ll have to watch for thunderstorms on this day, which should then break the heat. Forecast highs for next Wednesday and beyond are predicted to fall back into the 80s.