Three or more consecutive days of 90°F temperatures, high humidity, with nighttime temperatures that do not drop below 85°F causing a significant number of medically treated, heat-related illnesses or deaths.
This area of the State normally reaches 90°F 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
YEAR MONTH DAY TEMPERATURE (F)
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 90°F or greater. These months have not witnessed an official heat wave.
Onset of a heat wave is rapid
An official heat wave lasts for three or more consecutive days. Average heat waves are four days in duration.
A heat wave in this area of the State is a diffused event.
Copyright 2002, Wayne Cotterly