Fade particle emission rate over time

Hi all, new to scripting and to Unity in general. I have a rain particle system that I want to slowly fade out. I was able to disable the emission by setting the rate to 0. What I want to do is have the emission change from it's current value (200) to 0 over a few seconds. Would I use a lerp or something? Here's what I have so far.

     private ParticleSystem rainPart;
     bool beautifulDay;
 
     void Start () {
 
         rainPart = GetComponent<ParticleSystem>();
     }
 
     void Update () {
 
         if (beautifulDay) 
         {
             var emission = rainPart.emission;
             emission.rate = 0.0f;
         }
 
         if (Input.GetKeyDown (KeyCode.P)) 
         {
             beautifulDay = true;
         }
     
     }