Emil wrote:

Hi,

My location is Southern, CA zones 9-10. I have a lemon tree
who's leaves are curled upwards. Is this a sign of something?

Curled leaves on citrus often indicates spider mites, which can
defoliate a tree. They are too small to see without a magnifying
glass. The best treatment is malthion; add some liquid soap as a
wetting agent.
--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 19 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a)
Gardening pages at http://www.rossde.com/garden/