Sure, you can wear HEATTECH in the summer if you stay in Australia and New Zealand where winters are actually during the conventional summer months. But jokes aside, you probably don’t need to wear HEATTECH (base, extra warm or ultra warm) in warmer climates (anything higher than 16°C) if you’re a healthy individual. And you can probably wear regular HEATTECH base layers if you’re going to be in an air-conditioned environment. Other than that, we don’t really see why you would need to wear HEATTECH in the summer.