Pittsburgh’s weather in April can vary anywhere between 50 degrees Fahrenheit to 70 degrees Fahrenheit. You won’t have to pack for any snow (knock on wood!) but be prepared to pack clothes for weather near 40 Fahrenheit.
Once the date of PyCon is close, you can learn more by consulting the official 7-day forecast from the Weather Channel.
Keep in mind that conference room temperatures tend to fluctuate. Please wear clothes in layers, to ensure you are comfortable at all times. It can rain in spring time, so you might want to pack a light rain coat or umbrella.