Based on your photo, I would be hesitant. Is tonight your only option for brewing? If you don't have white sediment on the bottom, you have had little to no yeast activity. Did you get the yeast mail order? How long ago? During the hot spell? Did it smell foul or normal? Based on the appearance, you have have very little active yeast. But even if you have a little healthy yeast, it should eventually start to be active. In that case you would need to step it up a few times to get enough.
If you can get more yeast and really need to brew soon, get two smack packs and skip the starter, depending on your OG. If you have time and patience, consider it a challenge to build these little guys back to life.