Rainfall onset and offset count

[Thlama]

I have a yearly rainfall data from 1st Jan to 31st Jan.
I will like to count the number of days with rainfall of at least 20mm in 3 days.

Example:
Date. mm
1/1/2020 10
2/1/2020 18
3/1/2020 20
4/1/2020 26
5/1/2020 16
6/1/2020 24
7/1/2020 20
8/1/2020 23
9/1/2020 0
10/1/2020 18
11/1/2020 20
12/1/2020 26

 

[DRSteele]

Welcome to the forum.

The A4 formula might require entry with Ctrl+Shift+Enter.

MrExcel posts18.xlsx
	A	B
3	instances of at least 20 rain for at least 3 consecutive days
4	2
5
6	rain minimum	20
7	for days	3
8
9	date	rain
10	1/1/2020	10
11	1/2/2020	18
12	1/3/2020	20
13	1/4/2020	26
14	1/5/2020	16
15	1/6/2020	24
16	1/7/2020	20
17	1/8/2020	23
18	1/9/2020	0
19	1/10/2020	18
20	1/11/2020	20
21	1/12/2020	26
22	1/13/2020	0
23	1/14/2020	0
24	1/15/2020	0
25	1/16/2020	0
26	1/17/2020	0
27	1/18/2020	0
28	1/19/2020	0
29	1/20/2020	0
30	1/21/2020	0
31	1/22/2020	21
32	1/23/2020	21
33	1/24/2020	0
34	1/25/2020	0
35	1/26/2020	0
36	1/27/2020	0
37	1/28/2020	21
38	1/29/2020	20
39	1/30/2020	20
40	1/31/2020	21
Sheet63

Cell Formulas
Range	Formula
A3	A3	="instances of at least "&B6&" rain for at least "&B7&" consecutive days"
A4	A4	=SUMPRODUCT(--((FREQUENCY(IF(B10:B40>=B6,ROW(B10:B40)),IF(B10:B40<B6,ROW(B10:B40))))>=B7))