Write SQL query to solve given problem: Among all the trips, which day had the most bikes borrowed? What was the average coldest temperature on that day?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T2.date, AVG(T2.min_temperature_f) FROM trip AS T1 INNER JOIN weather AS T2 ON T2.zip_code = T1.zip_code GROUP BY T2.date ORDER BY COUNT(T1.start_date) DESC LIMIT 1