How to store a date without the year component

I have to store climate (temperature) data for a few cities. This would mean that each city will have 365 values (ex: The value for Jan 1, is the average temperature for that city for all Jan 1 for 50 years (1955-2004).

Hence I am not at all concerned with year. How do I store the date in a date column? Do I store Jan 1 as Jan 1 2009 ( a non-leap year)? Or is there any better way out?

a different approach

you can have a separate table to store all the dates, just like a Date dimension table and then in your main table have a foreign key pointing to it

CREATE TABLE YourDatesTable (
 DateID int NOT NULL IDENTITY(1, 1),
 [Date] datetime NOT NULL,
 [Year] int NOT NULL, 
 [Month] int NOT NULL,
 [Day] int NOT NULL
 CONSTRAINT PK_Dates PRIMARY KEY CLUSTERED (DateID)
)

Set the Dates Start and End

DECLARE @StartDate datetime
DECLARE @EndDate datetime

SET @StartDate = '01/01/1955'
SET @EndDate = '12/31/2004'

Generate the Date Records

DECLARE @LoopDate datetime
SET @LoopDate = @StartDate

WHILE @LoopDate <= @EndDate
BEGIN
 INSERT INTO YourDatesTable  VALUES (
  @LoopDate,
  Year(@LoopDate),
  Month(@LoopDate), 
  Day(@LoopDate)
)  

 SET @LoopDate = DateAdd(d, 1, @LoopDate)
END

View the Dates and notice that leap years have feb 29 and non leap years have only till feb 28

a non leap year

SELECT * FROM YourDatesTable 
where Month = 2
and Year = 2003

a leap year

SELECT * FROM YourDatesTable 
where Month = 2
and Year = 2004

you can use the DateID as a foreign key in your main table

This way you have day, month and year seperate and you also have the Date in dateformat for any date related functions

for reference
the script to generate a date dimension i used this site
http://www.sqlbook.com/Data-Warehousing/Date-Dimension-SQL-script-18.aspx

StackExchange Database Administrators Q#18389, answer score: 3