Extra water can help. Mulch if you haven't mulched already, and use an umbrella or put up a shade cloth for the heat wave expected this week. You can use old sheets or whatever for shade. It can keep you plant from being affected as badly as it was last time.

If it is exposed to dry hot winds, you could try planting around it to shelter it a little. Yes mulching and watering are good. Grevillea species like full sun generally to flower well but the umbrella suggested would be a good temporary solution. Of course, you could put it up every year during the hottest periods. Long term, maybe you could try growing close to a shady tree so it gets a little shade. Otherwise there are chemical spray products useful for both frost and heat protection. One that I have heard of is called Envy.