- hotter than normal/and cooler than normal; and
- more precipitation than normal/less precipitation than normal.
Thus, dark brown means it is very likely that temperatures will exceed the norm while dark blue would indicate that it was very likely for temperatures to be below normal. Notice that degree or intensity of deviation from the norm is not indicated, only probability.
Here's the prognosis for April, 2007 made mid-March:
For our rainy season -- July, August and September -- it looks likely we're significantly more likely to have a wetter and warmer period than historical averages: