I have a 15 year old Navel orange tree that is loaded with fruit right now. This tree experienced a lot of growth flush in Oct and Nov 09 because of the unusually warm fall/winter in my area (the last time I fertilized this tree was in June 09). And in Dec all of the new growth got burnt completely when the frosts hit us hard.
There are a few flowers this week on the tree but nowhere close to the hundreds upon hundreds of flowers that i am used to seeing each year. Is it too early for a flowering cycle or have I lost a year's worth of fruiting to the frost?

Frost or no frost, even the Washington Navels have the tendency to be alternate heavy bearer. If you allowed it to bear heavily last season, the following season would be a lousy one, then the next would be heavy. But I don't know how heavy is your previous fruiting to warrant a poor crop this coming season.

That is unusually early bloom you have there, thanks to the warm late fall and early winter. In heavy bearing years, the tree should be able to produce flowers during the normal bloom time even if it had early blooms in late fall to early winter. This is from my observations in my yard only. The textbooks may have a different information.

Thanks, Joe. The tree is loaded, but not unusually so.
It is weird to see blooms cropping up now - just a few here and there - but the last few days here have felt as if spring is in the air
What would you characterize as a normal bloom time for citrus in Northern California? At least based on the trees in your yard? TIA.

April is the craziest time of citrus blooms in my yard. Also comes with armies of bees.

The only exceptions are calamondins and lemons which blooms and fruit year round.

"Artificial Spring" has sprung inside my greenhouse. All of my citrus tree are putting out their first sprig flush. Even with only 1/2 hour of additional sunlight, the trees know that something has changed. Aphids will not be far behind. - Millet (1,092-)