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Published by Katie Stokes
The San Diego Temperature Data File
As of January 13, 2020, the source data file used as the basis this San Diego Annual Average Temperature graph is available for downloading.
The file is comma delimited, in the format of: Year, Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec - starting in 1852. The monthly figures are the average temperature for each month. The annual figure shown in the graph is computed by adding the 12 months and dividing by 12, the annual temperature computation is not weighted by the number of days in each month. Someday I'll produce a weighted graph and see how different it is. Very likely different by just a pixel or two or less for each year. Temperature data is in Fahrenheit with two decimals. I once read that the official rain gauge has a history of being in 9 different locations since records began, and I'm guessing this is also true for the official thermometer. I first constructed my data file perhaps 20 years ago and I've forgotten the sources for all the data, there were several. Anyone with "verified information or history" please contact me at firstname.lastname@example.org.
Of some interest: The NWS computes the average temperature for each month by adding the averages for each day and dividing by the number of days in the month. But, the average for each day is computed by taking the high and low for the day and dividing by 2! Wondering how different the average would be if the hourly temperatures were added and divided by 24? I suspect the divide by 2 method is used for historical continuity.
DOWNLOAD: File is here (sandiegotemp.txt). The data will come up as a separate page. It is easy to bring the data into a spreadsheet. Save the text page. Then open a spreadsheet program and import the data from the saved text file. Corrections welcome.
I will update the file once a year when I update the chart.
The overall presentation shows increasing temperatures.
January 1, 2020 note:
2020 was the 9th warmest in San Diego since records began in 1852, with an annual average of 66.01 reasserting the long term upward channel.
January 1, 2020 note:
2019 was the coolest in San Diego of the last six years. While 64.43 is still above the normal of 62.5, the reading is towards the low end of the long term upward channel. August was notably cooler than last year, coming in at 71.6 versus the much above normal 78.1.
January 1, 2019 note:
The streak of annual average temperatures above 66 degrees Fahrenheit continued with a record fifth year in a row in 2018. One month set a new record high average temperature, August with 78.1 degrees. January came up .2 degrees shy of its record of 61.7 at 61.5 degrees.
January 1, 2018 note:
Since 2014, when the warmest year (average 67.54 degrees Fahrenheit) was recorded in San Diego since records began in 1852, we've had three consecutive years with the annual average temperature above 66 degrees. This is impressive because 66 degrees was reached just three times in the prior 162 years! So four of the seven years with the average temperature above 66 degrees during the 166 year history belong to a current streak!