Heat Wave

Total Score=60


Three or more consecutive days of 90F temperatures, high humidity, with nighttime temperatures that do not drop below 85F causing a significant number of medically treated, heat-related illnesses or deaths.


This area of the State normally reaches 90F or greater at least five times per year. However, strings of three or more consecutive days of such temperatures are rare because of our latitude and proximity to the ocean and its cool breezes.


The following data is from the Lewiston Climatological Station


1876 July 16=91F 17th=91F 18th=97F 19th=94F

1876 August 6=91F 7th=95F 8th=93F 9th=91F

1878 June 30=94 F July 1st=94F 2nd=96F 3rd=90F

1882 July 24 =94F 25th=93F 26th=94F

1901 July 14=91F 15th=96F 16th=92F

1911 July 9=91F 10th=94F 11th=90F 12th=96F

1919 July 3=93F 4th=98F 5th=94F

1941 June 19=92F 20th=93F 21st=95F 26th=91F 27th=97F 28th=97F

1944 August 11=99F 12th=99F 13th=97F 14th=93F 15th=92F

1947 August 13=99F 14th=96F 15th=98F

1948 August 25=93F 26th=100F 27th=100F 28th=98F 29th=94F

1949 July 27=96 28th=94F 29th=95F 30th=98F

1949 July 26=95F 27th=97F 28th=92F

1952 July 13=90F 14th=94F 15th=92F 16th=91F

1953 August 28=93F 29th=96F 30th=95F 31st=91F

1955 August 20=91F 21st=94F 22nd=91F

1959 August 15=94F 16th=95F 17th=90F

1963 July 25=90F 26th=94F 27th=92F 28th=94F

1969 July 16=93F 17th=93F 18th=91F

1970 July 23=90F 24th=93F 25th=90F

1975 July 31=95F Aug 1st=98F 2nd=103F

1977 July 19=93F 20th=94F 21st=99F

1980 August 7=90F 8th=93F 9th=92F

1987 August 16-18

1989 July 25-27

1991 June 26-28

1993 July 7=94F 8th=92F 9th=94F 10th=98F 11th=93F

1993 August 26=92F 27th=94F 28th=93F


The Following Data is from the Poland NWS Cooperative Observer Station (#176856) (Records from August 1996)

1999 July 17=90F 18=93F 19=90F

2002 August 12=91F 13=92F 14=92F 15=94F 16=96F 17=92F 18=89F 19=90F 20=89F


Time of Year

June, July, and August present the greatest potential for a heat wave. May and September have occasionally experienced temperatures above 90F or greater. These months have not witnessed an official heat wave.


Speed of Onset

Onset of a heat wave is rapid


Duration of Event

An official heat wave lasts for three or more consecutive days. Average heat waves are four days in duration.


Area of Impact

A heat wave in this area of the State is a diffused event.


Copyright 2002, Wayne Cotterly

Revised: 10/21/02