It sounds like you may be experiencing allergic rhinitis that worsens in hot weather, especially at night. This condition often causes nasal congestion, mucus, and sneezing due to allergens or irritants triggered by heat.

• You might benefit from antihistamine and anti-inflammatory medications like Montelukast and Levocetirizine, which help reduce nasal swelling and block allergic reactions. These are available in combination tablets such as Montewok-LC, but should only be taken under a doctor's prescription.
• To ease symptoms at home, keep your sleeping area cool and well-ventilated, use a saline nasal spray to clear mucus, and avoid known allergens or irritants like strong perfumes or smoke.
• If symptoms persist or worsen, especially with difficulty breathing or severe discomfort, consult an allergist or an ear, nose, and throat (ENT) specialist for proper evaluation and tailored treatment.

If you want, I can explain how these medications work or suggest lifestyle adjustments to reduce your symptoms.To narrow down potential causes, we will need some more information.Please tell me your age and gender.