Yes. Sunny days can become special EVEN without Rainy days.
Sunny days imply days having sun and rainy days are those which are raining. they do not refer to the seasons SUMMER , RAINY... This question is not a simple one as to answer that rainy days are not suitable for playing and sunny days are quite suitable. What is that SPECIALITY is the question. Sun and rain are two sides of same coin. They are among five elements of NATURE- Pancha Bhootas. Sun heats water on the earth and evapouerates it to form Clouds. Clouds under certain atmospheric conditions begin to rain. Again that water is converted as clouds and so on.... The cycle continues. So sun is essential for the process of rains. Rains are necessary for cultivation and production of food items. Can we neglect rains and go on praising sun ?
Sunny days have their own SPECIALITY . I want to tell you few facts. (1). Sun is a powerful plannet in the galaxy. In VEDAS , Sun God is the source for Agni an embodiment of knowledge also. Hanuman learnt Vedas from Sun as per Ramayana. (2) By movement of Earth Sun is forming day and nights. (3). Sun rays are healthy. " AAROGYAM BHAASKARAA DICHCHET". We know people take Sun- bath for various reasons. They contain vit.D. (4). In Yoga SURYA NAMASKARAS take important place.
Inspire of the facts told now, RAINS and RAINY DAYS are not to be looked down. They give water for living. They develop forests. They fill tanks wells ponds and pools. They flow in rivers and so on. Sun is a sun rain is a rain . Both have their own specialities. After all ,for a temporary phase or momentary enjoyment one may say praise one and degrade the other. When the Sun is specially responsible for the processing of rain itself, the topic is to be confirmed in positive way.
In the given topic, stress is given on the DAYS ..not on sun or rain. If the speciality is of the day, no doubt, sunny days can't become special without existence of rainy days.