Often a company will give an earnings update.Depending on the company it is usually a bit conservative.SCL for example, always under promise and over deliver.
Brokers' research is pretty reliable,as is www.4-traders.com.
And yes general analysts; record cars sales means CMO,TNR and HBL will do well,
Drought/flood could affect PGW earnings .Hail storms,disease will affect SCL and SEK.
High NZ$ will be good for retailers such as WHS,HLG etc,and bad for exporters such as SCL.
Ageing population is good for the retirement and medical supply sectors,RYM,SUM EBO etc.