What is best airline & routing CA to Sydney? Also, how is the weather in February?

Best is relative. Are you a frequent flyer with any particular airline alliance?

February is good weather generally as it is Summer. I can be humid in February.

Quickest would probably be Los Angeles to Sydney direct. It's about 14 hours. If you stop anywhere, like Honolulu, or Auckland (with Air New Zealand) that will add on time to the journey. You could check the websites for Qantas, Virgin Australia, Air NZ. If you book via some of the American airlines it may turn out to be a codeshare. You can usually tell by the flight number.

Summer in Australia is Dec-Feb so it will likely be warm to hot. You can check historical weather on www.wunderground.com - under the More tab at the top.

Kay

Delta also has a daily nonstop 777 from LAX.

Look at kayak.com and spend several weeks/months looking at the prices that come up.

Hi

February is our hottest month of the year so expect temperatures up to mid 40s (celsius). Evenings remain hot and humid. Most flights from LAX will got direct to Melbourne, Sydney or Brisbane.

I've done that leg (SYD -LAX) on United. They are OK, not as great as the Asian airlines, but OK.

February is pretty roasty - pack loose clothing, but maybe bring a light cardigan or similar for the air conditioning.

Lavandula

Daughter works in Antarctica and says that folks who flew United had an old plane with movies in the ceiling and no free drinks on their flights. Delta and Qantas have free drinks,new airplanes and individual screens at each seat which made a big difference!