Heat Wave July 4-6 1999
East Coast US

A severe heat wave, with temperatures to 106 degrees, scorched the Eastern US from July 4-6 1999. Official (but unchecked) readings has temperatures to 106° (Ft. Eustis VA) and 104 (Ft. Belvoir VA), with a heat index of up to 120° (Petersburg VA). Power consumption was urged in D.C. and blackouts occurred in Manhattan, New York City for 70,000 customers, some into the next days. In New Jersey rolling blackouts affected 400,000 customers. At least eight deaths were attributed to the heat wave. The heat wave received national media coverage, for example this CNN article.

Please note with all the data below, these are unchecked, often automated, NWS observations. The NWS for the offices responsible may have rescended the readings. Where I saw fit I noted heat indices that were probably incorrect due to dewpoint sensor malfunctions.

• Temperature Plot Animation July 5-6 1999
  • Lows in the low-mid 80's; 86 at 5am in NYC; Highs to 104 in VA
• Heat Index Plot Animation July 5-6 1999
  • Low H.I. of 91 overnight in MD; 2 116's in VA; 112 in MA
• Temperatures > 95 on 7/5/99 East Coast - LIST (Large file)
  • Max Temp 104; Max Heat Index 116
• Temperatures > 95 on 7/6/99 East Coast -LIST (Large file)
  • Max Temp 106; Max Heat Index 120
• Temperatures > 100 on 7/6/99 East Coast - LIST
  • Max Temp 106; Max Heat Index 120
• Record Temperatures on 7/5/99 East Coast - LIST
  • 100 at D.C. & Roanoke; DE breaks 1901 record
• Temps vs. Normal 7/5/99 & Heat Indices - East Coast - LIST
  • Heat Index to 115
• Heat Advisories By County (US Map) - 7/5 Afternoon
  • 17 States under Heat Advisories!
• Heat Advisories By County (Regional Map) - 7/5 Afternoon
  • 17 States under Heat Advisories!
• US Temperatures - 4pm 7/5 - PSC
  • 102's in NE US
• US Heat Indices - 4pm 7/5 - PSC
  • 113 in PA
• CASI1 Weather Station at CASI HQ (State College PA) Stats for 7/5
  • High 94; Max Heat Index 105
• US High Temps 7/5 - TWC
  • Two 102's
• US High Temps 7/4 - TWC
  • 99's Galore!
• US Max Temps 7/5 - NWS DIFAX
  • 2 101's
• US Max Temps 7/6 - NWS DIFAX
  • 2 103's
• High Dewpoints 7/5 3pm - SE US
  • 2 82's (prob. bad), lots of upper 70's
• High Dewpoints 7/5 3pm - VA
  • 86 and 2 82's (prob. bad), lots of upper 70's
• US Heat Index 7/5 4:30pm - TWC
  • Two 110's
• Forecast Highs 7/6 - TWC
  • 102 In D.C.
• Temperatures - 3pm 7/5 - Northeast - PSU
  • Shows Maximum Area Near 100
• Temperatures - 3pm 7/5 - VA Area
  • 11 100's, 2 102's, 1 104!
• Heat Index 3pm 7/5 - VA Area
  • 127 (probably incorrect), 116 (more common)
• Heat Index 4pm 7/6 - Mid-Atlantic
  • 127 (probably incorrect), 116 (more common)
• Heat Index 5pm 7/6 - Mid-Atlantic
  • 121 (probably incorrect), 115 (more common), 112 in MA!
• Heat Index 4pm 7/6 - VA Area
  • 127, 124 (probably incorrect), 116 (more common)
• Max Temps 7/5 - DC Metro Area (NBC4Winds AWS Network)
  • 2 103's
• Max Temps 7/5 - VA Area (NBC4Winds AWS Network)
  • 105,106
• Washington DC (NBC4) Temperature/Heat Index Graphs July 3-7 1999
  • Temps >101 and Heat Indices >109
• Washington D.C. (DAA) Temperature Graph 7/5-7/7
  • 2 104's

© 1999 Central Atlantic Storm Investigators