Friday and Saturday are likely to be the hottest days, when highs reach the upper 90s to around 100. Factoring in the humidity, it will feel like 105 to 110 degrees.

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By the heat wave’s final day next Monday, the region will have posted eight straight days with highs of at least 90 — passing the year’s two previous longest streaks of six days.

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Just how hot?

Depending on your preference for computer models, highs Thursday through Sunday will range between 98 and 101 or 96 and 98 in Washington. The GFS model is most aggressive with the heat, predicting some triple-digit highs, while the European model caps temperatures several degrees lower:

GFS model forecast highs Thursday to Monday

Thursday: 98

Friday: 99

Saturday: 100

Sunday: 101

Monday: 90

European model forecast highs Thursday to Monday

Thursday: 94

Friday: 97

Saturday: 97

Sunday: 97

Monday: 93

Nighttime temperatures are also predicted to be unusually warm, with lows hovering near 80, or perhaps even a couple of degrees higher Friday through Sunday.

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Note that these temperatures are for the environment around downtown Washington. Cooler suburban areas, especially north and west of the city, will tend to be several degrees cooler — with highs mostly in the mid-90s and overnight lows in the 70s.

Punishing humidity

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Factoring in the humidity, it will feel several degrees hotter than the air temperature each day.

Afternoon heat index values should at least reach 100 every day through Monday, and may peak in the range of 105 to 110 degrees Friday and Saturday.

Dew point temperatures, an indicator of humidity, should generally hover between 70 and 75 degrees — in the muggy range. Sunday and Monday, it would not be surprising to even see some dew points above 75, entering the sultry range.

Records?

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As this heat wave coincides with our hottest time of year historically, some of the records will be tough to match. For example, Thursday’s record high of 106, set in 1930, matches the highest temperature ever recorded in Washington. We won’t threaten that one. In fact, none of the record highs through Monday seem to be in peril. These are the existing record highs and the years they were set:

July 20: 106 from 1930

July 21: 104 from 1926

July 22: 103 from 1926

July 23: 102 from 2011

July 24: 101 from 2010

Heat readiness tips

As long as this heat lasts, remember the following tips to stay safe and cool: