Extreme rain in United States, 20 to 23 September 2023

Name: Extreme rain in United States, 20 to 23 September 2023
Start: 2023-09-20
End: 2023-09-23
Location: United States

Extreme rain in United States, 20 to 23 September 2023: 150 records at 135 stations, peak on 22 September 2023. Closed.

Data as of 2026-10-17. Last revised 17 October 2026 (2026-10-17).

Key Facts

Extreme rain in United States, 20 to 23 September 2023 set or tied 150 station records at 135 stations.
It ran from 20 September 2023 to 23 September 2023 (4 days) and its peak day was 22 September 2023.
Status: closed.
Helena AP ASOS set a daily record precipitation of 32.0 mm (1.3 in) on 22 September 2023.
The busiest day was 22 September 2023 with 69 records.
The oldest broken record in the ranked list had stood for 113 years.

Footprint

20 to 23 September 2023

The area covered by Extreme rain in United States, 20 to 23 September 2023 is outlined, with 20 of the stations that set records marked, coloured by record type. Made with Natural Earth.

Footprint of Extreme rain in United States, 20 to 23 September 2023: stations that set records in the event
Station	Type	Value	Date
Helena AP ASOS	Record daily precipitation	32.0 mm (1.3 in)	2023-09-22
Busby	Record daily precipitation	40.4 mm (1.6 in)	2023-09-22
Colstrip	Record daily precipitation	38.4 mm (1.5 in)	2023-09-22
Divide	Record daily precipitation	45.7 mm (1.8 in)	2023-09-22
Lewistown AP	Record daily precipitation	25.9 mm (1.0 in)	2023-09-22
Arbuckle Mtn	Record daily precipitation	30.5 mm (1.2 in)	2023-09-21
Conrad	Record daily precipitation	36.8 mm (1.4 in)	2023-09-22
Forsyth	Record daily precipitation	57.9 mm (2.3 in)	2023-09-22
Cohagen	Record daily precipitation	37.6 mm (1.5 in)	2023-09-22
Ingomar 9 E	Record daily precipitation	39.4 mm (1.6 in)	2023-09-22
Leiter 9N	Record daily precipitation	34.0 mm (1.3 in)	2023-09-22
Grace	Record daily precipitation	19.1 mm (0.8 in)	2023-09-20
Jackson	Record daily precipitation	23.1 mm (0.9 in)	2023-09-21
Lucky Strike	Record daily precipitation	22.9 mm (0.9 in)	2023-09-21
Derr.	Record daily precipitation	22.9 mm (0.9 in)	2023-09-21
Snow Mountain	Record daily precipitation	17.8 mm (0.7 in)	2023-09-21
Pendleton	Record daily precipitation	12.4 mm (0.5 in)	2023-09-21
Lima	Record daily precipitation	17.8 mm (0.7 in)	2023-09-22
Malmstrom AFB	Record daily precipitation	20.6 mm (0.8 in)	2023-09-22
Ft Benton	Record daily precipitation	17.8 mm (0.7 in)	2023-09-23

Records per Day

Peak day 69

Records set or tied each day from 20 September 2023 to 23 September 2023. The most in one day was 69 on 22 September 2023.

Top Records by Margin

Margin over the record replaced

Top records of Extreme rain in United States, 20 to 23 September 2023 ranked by margin
Divide, 09-22	40.6 mm (1.6 in)
Forsyth, 09-22	34.8 mm (1.4 in)
Ingomar 9 E, 09-22	28.7 mm (1.1 in)
Arbuckle Mtn, 09-21	25.4 mm (1.0 in)
Cohagen, 09-22	25.4 mm (1.0 in)
Helena AP ASOS, 09-22	24.6 mm (1.0 in)
Colstrip, 09-22	23.2 mm (0.9 in)
Busby, 09-22	22.1 mm (0.9 in)
Leiter 9N, 09-22	22.1 mm (0.9 in)
Derr., 09-21	20.4 mm (0.8 in)
Lucky Strike, 09-21	15.3 mm (0.6 in)
Snow Mountain, 09-21	15.3 mm (0.6 in)
Malmstrom AFB, 09-22	15.3 mm (0.6 in)
Lewistown AP, 09-22	13.2 mm (0.5 in)
Conrad, 09-22	8.9 mm (0.35 in)

Margin is how far the new value is beyond the record it replaced. Ties are not shown.

Margin Against Age of the Broken Record

150 records plotted by how far they beat the old record (across) and how many years the old record had stood (up). Long standing records beaten by a wide margin sit in the top right.

Margin against age of the broken record in Extreme rain in United States, 20 to 23 September 2023
Margin (mm)	Years the old record stood
25	77
22	112
23	93
41	45
13	113
25	40
20	40
15	72
9	77
15	33
9	88
6	89
5	112
35	16
15	34
4	93
25	16
29	16
4	93
22	16
6	77
11	60
1	109
6	77
10	57
2	93
16	45
9	60
17	16
20	16
8	54
18	6
14	6
9	45
12	16
7	38
2	72
3	54
20	6
5	36
10	37
15	6
10	22
0	68
4	54
1	64
3	60
20	24
15	0
8	4
17	12
9	6
1	68
8	38
4	57
13	0
10	22
1	52
8	22
10	22
8	38
8	38
10	9
11	12
12	16
5	38
7	16
11	22
8	38
10	0
8	22
6	42
2	45
5	38
5	37
2	45
2	52
6	8
7	5
13	17
13	22
7	5
0	49
10	6
7	4
1	38
5	16
5	16
1	49
8	22
5	22
10	6
9	4
6	5
5	22
6	5
3	16
8	17
2	32
5	16
5	16
4	16
1	38
3	24
9	6
3	5
3	6
8	4
5	16
3	25
5	16
3	16
2	16
1	14
5	6
3	16
5	14
2	14
2	6
0	25
3	16
8	0
3	16
1	22
2	12
1	16
3	16
3	16
3	16
3	16
5	0
3	16
1	6
4	0
5	9
3	8
1	8
3	5
3	4
3	6
3	6
3	0
0	5
1	6
1	5
3	5
3	0
3	0
1	0
1	5

Compared With Other Events

Station records per event

Station records in Extreme rain in United States, 20 to 23 September 2023 compared with similar events
Extreme rain in United States and Mexico, 23 February to 15 March 2019	2,223 records
Extreme rain in United States, 3 to 19 January 2024	2,133 records
Extreme rain in Australia, 7 to 26 March 2021	2,099 records
Extreme rain in United States and Mexico, 29 September to 19 October 2018	1,970 records
Extreme rain in United States, 19 December 2022 to 13 January 2023	1,941 records
Extreme rain in United States, 20 to 23 September 2023 (this event)	150 records

Every Record Set

20 of 150

Every record set or tied during Extreme rain in United States, 20 to 23 September 2023, in date order
Date	Station	Record	Value	Margin	Years stood	Significance
2023-09-20	Grace	Record daily precipitation	19.1 mm (0.8 in)	3.9 mm (0.15 in)	93	20 of 100 (Routine)
2023-09-21	Arbuckle Mtn	Record daily precipitation	30.5 mm (1.2 in)	25.4 mm (1.0 in)	40	56 of 100 (Notable)
2023-09-21	Jackson	Record daily precipitation	23.1 mm (0.9 in)	3.5 mm (0.14 in)	93	20 of 100 (Routine)
2023-09-21	Lucky Strike	Record daily precipitation	22.9 mm (0.9 in)	15.3 mm (0.6 in)	34	20 of 100 (Routine)
2023-09-21	Derr.	Record daily precipitation	22.9 mm (0.9 in)	20.4 mm (0.8 in)	40	20 of 100 (Routine)
2023-09-21	Snow Mountain	Record daily precipitation	17.8 mm (0.7 in)	15.3 mm (0.6 in)	33	20 of 100 (Routine)
2023-09-21	Pendleton	Record daily precipitation	12.4 mm (0.5 in)	6.0 mm (0.24 in)	89	20 of 100 (Routine)
2023-09-22	Helena AP ASOS	Record daily precipitation	32.0 mm (1.3 in)	24.6 mm (1.0 in)	77	71 of 100 (Major)
2023-09-22	Busby	Record daily precipitation	40.4 mm (1.6 in)	22.1 mm (0.9 in)	112	68 of 100 (Major)
2023-09-22	Colstrip	Record daily precipitation	38.4 mm (1.5 in)	23.2 mm (0.9 in)	93	65 of 100 (Major)
2023-09-22	Divide	Record daily precipitation	45.7 mm (1.8 in)	40.6 mm (1.6 in)	45	63 of 100 (Major)
2023-09-22	Lewistown AP	Record daily precipitation	25.9 mm (1.0 in)	13.2 mm (0.5 in)	113	62 of 100 (Major)
2023-09-22	Conrad	Record daily precipitation	36.8 mm (1.4 in)	8.9 mm (0.35 in)	88	49 of 100 (Notable)
2023-09-22	Forsyth	Record daily precipitation	57.9 mm (2.3 in)	34.8 mm (1.4 in)	16	45 of 100 (Notable)
2023-09-22	Cohagen	Record daily precipitation	37.6 mm (1.5 in)	25.4 mm (1.0 in)	16	43 of 100 (Notable)
2023-09-22	Ingomar 9 E	Record daily precipitation	39.4 mm (1.6 in)	28.7 mm (1.1 in)	16	43 of 100 (Notable)
2023-09-22	Leiter 9N	Record daily precipitation	34.0 mm (1.3 in)	22.1 mm (0.9 in)	16	43 of 100 (Notable)
2023-09-22	Lima	Record daily precipitation	17.8 mm (0.7 in)	8.7 mm (0.34 in)	77	20 of 100 (Routine)
2023-09-22	Malmstrom AFB	Record daily precipitation	20.6 mm (0.8 in)	15.3 mm (0.6 in)	72	20 of 100 (Routine)
2023-09-23	Ft Benton	Record daily precipitation	17.8 mm (0.7 in)	5.1 mm (0.20 in)	112	20 of 100 (Routine)

The daily ledgers keep a limited number of records per day, so this list has 20 of the 150 records the event counts. The counts above use the full total.

Related Headlines

Third party news, headline and link only

Download the Data

Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-17. Events are found by this site from station records and are not official designations. Records are provisional until reprocessed.

Margin (mm)	Years the old record stood
25	77
22	112
23	93
41	45
13	113
25	40
20	40
15	72
9	77
15	33
9	88
6	89
5	112
35	16
15	34
4	93
25	16
29	16
4	93
22	16
6	77
11	60
1	109
6	77
10	57
2	93
16	45
9	60
17	16
20	16
8	54
18	6
14	6
9	45
12	16
7	38
2	72
3	54
20	6
5	36
10	37
15	6
10	22
0	68
4	54
1	64
3	60
20	24
15	0
8	4
17	12
9	6
1	68
8	38
4	57
13	0
10	22
1	52
8	22
10	22
8	38
8	38
10	9
11	12
12	16
5	38
7	16
11	22
8	38
10	0
8	22
6	42
2	45
5	38
5	37
2	45
2	52
6	8
7	5
13	17
13	22
7	5
0	49
10	6
7	4
1	38
5	16
5	16
1	49
8	22
5	22
10	6
9	4
6	5
5	22
6	5
3	16
8	17
2	32
5	16
5	16
4	16
1	38
3	24
9	6
3	5
3	6
8	4
5	16
3	25
5	16
3	16
2	16
1	14
5	6
3	16
5	14
2	14
2	6
0	25
3	16
8	0
3	16
1	22
2	12
1	16
3	16
3	16
3	16
3	16
5	0
3	16
1	6
4	0
5	9
3	8
1	8
3	5
3	4
3	6
3	6
3	0
0	5
1	6
1	5
3	5
3	0
3	0
1	0
1	5

Margin (mm)	Years the old record stood
25	77
22	112
23	93
41	45
13	113
25	40
20	40
15	72
9	77
15	33
9	88
6	89
5	112
35	16
15	34
4	93
25	16
29	16
4	93
22	16
6	77
11	60
1	109
6	77
10	57
2	93
16	45
9	60
17	16
20	16
8	54
18	6
14	6
9	45
12	16
7	38
2	72
3	54
20	6
5	36
10	37
15	6
10	22
0	68
4	54
1	64
3	60
20	24
15	0
8	4
17	12
9	6
1	68
8	38
4	57
13	0
10	22
1	52
8	22
10	22
8	38
8	38
10	9
11	12
12	16
5	38
7	16
11	22
8	38
10	0
8	22
6	42
2	45
5	38
5	37
2	45
2	52
6	8
7	5
13	17
13	22
7	5
0	49
10	6
7	4
1	38
5	16
5	16
1	49
8	22
5	22
10	6
9	4
6	5
5	22
6	5
3	16
8	17
2	32
5	16
5	16
4	16
1	38
3	24
9	6
3	5
3	6
8	4
5	16
3	25
5	16
3	16
2	16
1	14
5	6
3	16
5	14
2	14
2	6
0	25
3	16
8	0
3	16
1	22
2	12
1	16
3	16
3	16
3	16
3	16
5	0
3	16
1	6
4	0
5	9
3	8
1	8
3	5
3	4
3	6
3	6
3	0
0	5
1	6
1	5
3	5
3	0
3	0
1	0
1	5

Margin (mm)	Years the old record stood
25	77
22	112
23	93
41	45
13	113
25	40
20	40
15	72
9	77
15	33
9	88
6	89
5	112
35	16
15	34
4	93
25	16
29	16
4	93
22	16
6	77
11	60
1	109
6	77
10	57
2	93
16	45
9	60
17	16
20	16
8	54
18	6
14	6
9	45
12	16
7	38
2	72
3	54
20	6
5	36
10	37
15	6
10	22
0	68
4	54
1	64
3	60
20	24
15	0
8	4
17	12
9	6
1	68
8	38
4	57
13	0
10	22
1	52
8	22
10	22
8	38
8	38
10	9
11	12
12	16
5	38
7	16
11	22
8	38
10	0
8	22
6	42
2	45
5	38
5	37
2	45
2	52
6	8
7	5
13	17
13	22
7	5
0	49
10	6
7	4
1	38
5	16
5	16
1	49
8	22
5	22
10	6
9	4
6	5
5	22
6	5
3	16
8	17
2	32
5	16
5	16
4	16
1	38
3	24
9	6
3	5
3	6
8	4
5	16
3	25
5	16
3	16
2	16
1	14
5	6
3	16
5	14
2	14
2	6
0	25
3	16
8	0
3	16
1	22
2	12
1	16
3	16
3	16
3	16
3	16
5	0
3	16
1	6
4	0
5	9
3	8
1	8
3	5
3	4
3	6
3	6
3	0
0	5
1	6
1	5
3	5
3	0
3	0
1	0
1	5