Would i be able to get a job in cairns australia for a month and a half?

I live in Cairns

I would avoid wet season (nov-mar). There are fewer jobs in the northern half of Australia during this time as most of the tourists avoid this time of year. If you go when it's dry season, the tourist haunts are always looking for staff.

My advice to you would be when it's wet season in the north, do the southern part as it will be summer and more pleasant and then head north for dry season. Jobs are more abundant in the south in summer and in the dry season up north. Obviously assuming you plan visiting both regions :-)

Have fun!

Try fruit picking of some sort. I know that banana pickers/packers are in high demand. The same applies to Sugar cane. Have a look at this website:
http://www.bananabarracks.com/work.html
The Australian government also reward backpackers an extra year on their working holiday visa if they work 3 or more months as a farm hand/fruit picker.

If you stay in hostels, usually they have a board up with info on job vacancies in the area - some of them are even immediate start. Various hostels also take on backpackers to work reception, etc in exchange for a small wage and/or free lodgings. You can also check with hotels in the city to see if they are hiring staff, and some boats take on backpackers too.

My hubby and I were in Cairns at the beginning of June this year and lots of the restaurants on the Esplanade were wanting waiting staff, over at the Pier one of the bars wanted bar staff and waiting staff, it seemed fairly easy to get a job there especially for students on gap years, Cairns is a beautiful place, have fun and enjoy yourself when you go, good luck.