National Rankings

National Data Info
Palmer Drought Severity Index (PDSI), Palmer Hydrological Drought Index (PHDI), and Palmer Modified Drought Index (PMDI) are not offered for multiple-month time scales.

Contiguous U.S.

Precipitation Rankings, May 1978

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  • Record Wettest
PeriodValue1901-2000
Mean		AnomalyRank
(1895-2022)		Wettest/Driest
Since		Record
May 1978
1-Month		3.64"
(92.46mm)		2.91"
(73.91mm)		0.73"
(18.55mm)		117th Driest
Driest since:
1934
12th Wettest
Wettest since:
2019
Apr–May 1978
2-Month		6.18"
(156.97mm)		5.43"
(137.92mm)		0.75"
(19.05mm)		106th Driest
Driest since:
1934
23rd Wettest
Wettest since:
1957
Mar–May 1978
3-Month		8.44"
(214.38mm)		7.94"
(201.68mm)		0.50"
(12.70mm)		94th Driest
Driest since:
1925
35th Wettest
Wettest since:
1957, 1991
Feb–May 1978
4-Month		10.21"
(259.33mm)		10.07"
(255.78mm)		0.14"
(3.55mm)		74th Driest
Driest since:
1925
55th Wettest
Wettest since:
2019
Jan–May 1978
5-Month		13.39"
(340.11mm)		12.39"
(314.71mm)		1.00"
(25.40mm)		103rd Driest
Driest since:
1934
26th Wettest
Wettest since:
2019
Ties: 2011
Dec 1977–May 1978
6-Month		16.11"
(409.19mm)		14.73"
(374.14mm)		1.38"
(35.05mm)		106th Driest
Driest since:
1931
22nd Wettest
Wettest since:
2019
Nov 1977–May 1978
7-Month		18.97"
(481.84mm)		16.96"
(430.78mm)		2.01"
(51.06mm)		111th Driest
Driest since:
1934
17th Wettest
Wettest since:
1983
Oct 1977–May 1978
8-Month		21.16"
(537.46mm)		19.13"
(485.90mm)		2.03"
(51.56mm)		110th Driest
Driest since:
1934
18th Wettest
Wettest since:
2019
Ties: 1903
Sep 1977–May 1978
9-Month		24.38"
(619.25mm)		21.62"
(549.15mm)		2.76"
(70.10mm)		117th Driest
Driest since:
1934
11th Wettest
Wettest since:
2019
Ties: 1927
Aug 1977–May 1978
10-Month		27.93"
(709.42mm)		24.25"
(615.95mm)		3.68"
(93.47mm)		122nd Driest
Driest since:
1918
6th Wettest
Wettest since:
2019
Jul 1977–May 1978
11-Month		30.49"
(774.45mm)		27.03"
(686.56mm)		3.46"
(87.89mm)		120th Driest
Driest since:
1931
8th Wettest
Wettest since:
2019
Jun 1977–May 1978
12-Month		32.98"
(837.69mm)		29.95"
(760.73mm)		3.03"
(76.96mm)		115th Driest
Driest since:
1934
13th Wettest
Wettest since:
2019
Dec 1976–May 1978
18-Month		45.19"
(1,147.83mm)		44.70"
(1,135.38mm)		0.49"
(12.45mm)		69th Driest
Driest since:
1931
58th Wettest
Wettest since:
2019
Jun 1976–May 1978
24-Month		58.70"
(1,490.98mm)		59.92"
(1,521.97mm)		-1.22"
(-30.99mm)		38th Driest
Driest since:
1931
89th Wettest
Wettest since:
2020
Jun 1975–May 1978
36-Month		88.60"
(2,250.44mm)		89.88"
(2,282.95mm)		-1.28"
(-32.51mm)		43rd Driest
Driest since:
1955
83rd Wettest
Wettest since:
2019
Jun 1974–May 1978
48-Month		120.71"
(3,066.03mm)		119.78"
(3,042.41mm)		0.93"
(23.62mm)		64th Driest
Driest since:
1956
61st Wettest
Wettest since:
2019
Jun 1973–May 1978
60-Month		153.95"
(3,910.33mm)		149.64"
(3,800.86mm)		4.31"
(109.47mm)		90th Driest
Driest since:
1957
34th Wettest
Wettest since:
2020

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