INTRODUCTION 



The monthly and yearly mean and extreme surface water 

 temperatures given on the following pages are obtained 

 from observations made through 1946. The data were recorded 

 principa lly at t ide stations maintained by the U. S. Coast 

 and Geodetic Survey along the Atlantic and Gulf coasts of 

 the United States and in Greenland and Bermuda. There are 

 also included monthly mean and extreme temperatures for 

 Ba Iboa and Cristoba 1 which were furnished by the Department 

 of Operation and Maintenance, The Panama Canal. 



The daily temperature observations are taken at what- 

 ever time the tide observer services the tide gage. The 

 visits are usually made during daylight hours, and it may 

 be assumed that in the course of a year the distribution 

 of the observations is fairly uniform over all phases of 

 the tide. The water samples are drawn with a bucket from 

 near the surface and may be regarded as representative of 

 the first one or two feet of water. Thermometer readings 

 are made in the bucket immediately after the sample has 

 been drawn and before it has become affected appreciably 

 by the temperature of the surrounding air. When ice has 

 prevented the observation of water temperatures at some 

 North Atlantic stations, temperatures based on the freezing 

 point of water at each station have been inferred and used 

 in computing monthly means. 



Recording thermometers, recently installed at a few 

 stations, give continuous records of the temperatures of 

 the water a foot or two below extreme low water. 



An expectancy range table is included for each station 

 for which there are five or more years of observations. 

 The table shows the percentage of the individual tempera- 

 ture readings which agree with the monthly means within 

 the indicated limits. Graphs showing mean temperature 

 variations during the month and year and monthly extreme 

 temperatures are also included for these places. The un- 

 usual shape of the temperature curve for Daytona Beach 

 reflects the upwelling which occurs along this section 

 of the coast during the summer months. 



All temperatures in this publication are given in 

 degrees Fahrenheit. A table for converting into degrees 

 centigrade is provided on the inside back cover. 



The following publications complete this series and 

 may be obtained from the Director, U. S. Coast and Geodetic 

 Survey, Washington (25), D. C. : 



TW-2. Surface Water Temperatures, Pacific Coast. 

 DW - 1 . Density of Sea Water, At lant ic and Gulf Coasts. 

 DW-2. Density of Sea Water, Pacific Ocean. 



