It is summer now and in most of the following months. Fall would start at September or so.
You can find foreigners around San Jing Jie, there are many bars. There are English corners at Zhong Shan Square and Hong Qi Square, there you can find people speaking English almost every night.

I have been to Shenyang for 2 weeks holiday.
Just get prepated for the air pollution there mate, and it will be difficult to find people to speak english. Get a map here, i cant even seem to buy a map here in english. And be prepared for traffic madness too,seems people here horn to breathe. And you have to be on the lookout for cars if you walk across roads even on green walk lights, pedestrians or even walkways as you never know where the cars are coming from. Bring ipod along if you cant stand the car horns, people here love their car horns, they do it every few seconds. Oh and the people here spit everywhere, its horrible, just be prepared and just get used to it.
Have a good trip and be prepared for the cultural shock.

July is the hottest month of the year with an average temperature of 24.7C. Summer tends to be pretty humid and it rains a lot. Autumn is short but is sunny nearly everyday. Late summer, middle autumn are the best times to be in Shenyang, your lucky!

I don't know any exact percentages of English speakers here but I think there are a lot more than meets the eye. Many young people and older affluent business people can speak a little bit of English. On the downside, nearly all taxi drivers, street sellers, shop owners and workers, police officers, and other common people can not speak English, even a little. Shenyang is not like Beijing, the foreigners are few, and communication can be difficult for travelers with no Chinese skills.