For the far-future accuracy, look at the percentiles. Compare: http://weatherspark.com/#app;a=USA/CA/San_Francisco;t0=01/01;t1=12/31 http://weatherspark.com/#a

For the far-future accuracy, look at the percentiles. Compare: http://weatherspark.com/#app;a=USA/CA/San_Francisco;t0=01/01;t1=12/31 http://weatherspark.com/#app;a=USA/CA/San_Francisco;t0=01/01... To http://weatherspark.com/#app;a=USA/HI/Honolulu;t0=01/01;t1=12/31 http://weatherspark.com/#app;a=USA/HI/Honolulu;t0=01/01;t1=1... The temperature spread (10th to 90th percentile) in late September for SF is 64F to 82F for a delta of 18F - it can be very nice, but it can also be kind of crappy. In Honolulu the temp spread in August is 86F to 91F for a delta of only 5F - it's pretty sure it's going to be nice.