temperature control

Today was cloudy and chilly all day long. Then the temperature of the marquee was constantly 13-15 ℃. Salad looks very happy but this was not warm enough for other veg such as tomato, pepper, cucumber and soya beans. When sun comes out, temperature reaches 30 ℃, which is obviously too hot for salad and brassica. Leaves will get hard and bolt soon with heat. I started taking out seedlings of salad outside to harden off, planning to transplant them next week. People say it is too early but who ever know the future weather? I also planted out santona and more lettuce inside for safety.