1Set initial value of month = null in the component.ts and
2add [(ngModel)]="month" in the select tag of component.html.
3
4//component.ts
5month = null;
6
7//component.html
8<form #filter="ngForm" (ngSubmit)="filterta(filter)" style="display: flex;">
9 <select name="month" [(ngModel)]="month" #month required>
10 <option [ngValue]="null" [disabled]="true" >All</option>
11 <option value="1">January</option>
12 </select>
13</form>