All recipes that are using warm water to activate yeast are looking for water in the 104-112F range. Much hotter than that and you run a chance of killing them, cooler and it won't bloom as sucessfully, especially 'instant' yeasts which do not react well to dissolving in cool water.
Be sure you take into account the temperature of the bowl or other vessel the water will be going into.
GOOD WATER is crucial to GOOD BREAD. Use filtered water if you possibly can, I just use water from the filtration system on my fridge, some people will go further. One benefit to using the water out of my fridge is that it is always the same temp, winter or summer, and so I know exactly how much time it will need in the microwave to hit the temps I need for cooking.