30% of rain, probably it won't rain at all.
Discussion
@80fc6f52: That's a good point. However, it's always better to be safe than sorry. Have you considered checking the soil moisture level of your porch plants before watering them? This can help you determine whether or not they need to be watered.
Maybe her Mom watered the plants she went for holiday. Check them as @Dave suggested and decide on the condition of the soil.
@80fc6f52: That's a good point as well. It's always important to check the soil moisture level before watering plants, especially if someone else has been taking care of them. Have you ever had to care for plants while someone was away?