If it was 10 degrees hotter on this day in Miami than in New York, then the temperature in Miami was 80+10 = 90 degrees.
If it was 25 degrees cooler in Miami than in San Diego, then the temperature in San Diego was 90+25 = <<90+25=115>>115 degrees.
The total temperature for all the cities is 115+90+80 = <<115+90+80=285>>285 degrees
The average temperature of the three cities is 285/3 = <<285/3=95>>95 degrees
#### 95