I declare summer whenever there’s going to be 7 consecutive days in a row above 19 degrees.  And as such:

Friday            Max 22  Shower or two.    
17/09/11  Min 10  Max 25  Shower or two developing.    
18/09/11  Min 12  Max 21  Sunny.    
19/09/11  Min 11  Max 27  Showers developing. Windy.
20/09/11  Min 12  Max 20  Shower or two.     
21/09/11  Min 13  Max 22  Morning shower or two.    
22/09/11  Min 12  Max 24  Mostly sunny.

Summer.

In September.

It’s a good thing that global warming is a beat up by the greens, a front for communist interests trying to take control of our lives and introduce excessive and unneeded regulation – or else I might be worried.

I have a algorithm for detecting summer. Seven consecutive days in a row with a temperature of or above 20 degrees Celsius. I give you Summer, from the Bureau’s seven day forecast for Melbourne:
Forecast for Monday Max 20
Forecast for Tuesday Min 8 Max 24
Forecast for Wednesday Min 10 Max 25
Forecast for Thursday Min 12 Max 28
Forecast for Friday Min 16 Max 29
Forecast for Saturday Min 18 Max 28
Forecast for Sunday Min 16 Max 26
I should also point out that I consider there to be two seasons in Melbourne: Nice-but-hot (summer-ish) and a-bit-iffy (winter-ish).

I have a algorithm for detecting summer. Seven consecutive days in a row with a temperature of or above 20 degrees Celsius. I give you Summer, from the Bureau’s seven day forecast for Melbourne:

Thursday      Fine.                                  Min  6    Max 21
Friday        Mainly fine.                           Min 12    Max 25
Saturday      Fine.                                  Min 12    Max 30
Sunday        Shower or two.                         Min 15    Max 22
Monday        Fine.                                  Min 10    Max 23
Tuesday       Fine.                                  Min 12    Max 28

I swear, this gets earlier and earlier each year.