Tri-Cities weather in May

In May, Tri-Cities sees average daytime highs of 77°F and overnight lows near 52°F, with 0.7 in of rain across 4.5 wet days and about 14.7 hours of daylight. It is the 5th-warmest and 7th-wettest month of the year here.

Highs climb over the month, from about 74°F in the first days to 81°F by the end. The sky is clear or mostly clear about 31% of the time in May, and the air most often feels dry.

Daylight stretches from about 14 h 06 min at the start of May to 15 h 18 min by month's end. Set against the rest of the year, May is Tri-Cities's 6th-clearest and 3rd-windiest month. For the whole year in context, see Tri-Cities's year-round climate.

Daytime high
77°
5th warmest
Overnight low
52°
8th coldest
Rainfall
0.7 in
4.5 wet days
Daylight
14 h 48 min
4:30 AM – 7:16 PM
Cloud cover
56%
6th clearest
Wind
7 mph
3rd windiest
Solar energy
6.86 kWh/m²
Travel score
7.6
out of 10

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 74°F in the first days to 81°F by the end.

A typical May day in Tri-Cities reaches about 77°F in the afternoon and slips back to 52°F overnight — a 25°F spread between the day's warmth and the night's chill. On most days the high lands between 66°F and 91°F. Set against its neighbours, May runs about 10°F warmer than April and about 7°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
17348
27348
37448
47449
57449
67549
77549
87550
97650
107650
117651
127751
137751
147752
157752
167852
177853
187853
197853
207953
217954
227954
237954
248054
258055
268055
278055
288055
298155
308155
318156

How May really feels in Tri-Cities

Once humidity and wind are folded in, May averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Tri-Cities weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan41° / 29°1.38.12.38.80.2
Feb48° / 32°0.96.21.3102.0
Mar58° / 38°0.95.90.411.64.6
Apr68° / 44°0.74.9013.36.9
May77° / 52°0.74.5014.77.6
Jun84° / 58°0.52.8015.56.6
Jul93° / 64°0.11015.23.9
Aug92° / 62°0.210144.5
Sep81° / 54°0.31.8012.37.7
Oct66° / 44°0.95010.76.7
Nov50° / 35°1.17.30.79.22.4
Dec41° / 29°1.48.42.48.50.1

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 31% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 20% of May, with mostly cloudy or overcast conditions the remaining 49%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15248
25248
35248
45248
55248
65248
75149
85149
95050
105050
115050
124951
134951
144852
154852
164852
174951
184852
194852
205050
215050
225149
235149
245347
255347
265446
275545
285545
295644
305545
315644

Chance of precipitation in May

Any precipitation

Tri-Cities gets around 0.7 in of rain over 4.5 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 15% and peaks near 17% on the wettest days.

0%10%20%30%151015202531
Rain chance (%)
113
213
313
413
513
613
713
813
914
1014
1115
1215
1316
1416
1517
1617
1717
1817
1917
2017
2117
2216
2316
2415
2515
2614
2714
2814
2913
3013
3113

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

Most of May feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, May lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in May

Winds average 7 mph in May.

Across May, daily wind ranges from about 7 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm
317calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 14 h 06 min at the start of May to 15 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 72 minutes over May. Sunrise moves from 4:51 AM to 4:16 AM, and sunset from 6:57 PM to 7:32 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.14:516:57
214.14:506:58
314.24:486:59
414.24:477:01
514.34:457:02
614.34:447:03
714.44:427:05
814.44:417:06
914.54:397:07
1014.54:387:08
1114.64:367:10
1214.64:357:11
1314.64:347:12
1414.74:337:13
1514.74:317:15
1614.84:307:16
1714.84:297:17
1814.84:287:18
1914.94:277:20
2014.94:267:21
2115.04:257:22
2215.04:237:23
2315.04:237:24
2415.14:227:25
2515.14:217:26
2615.14:207:27
2715.24:197:28
2815.24:187:29
2915.24:177:30
3015.24:177:31
3115.34:167:32

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 6.86 kWh/m².

For context, solar energy here swings from a low near 1.26 kWh/m² to a high of 7.85 kWh/m² in July across the year — May's 6.86 kWh/m² sits near the top of that range.

02468151015202531
Solar energy (kWh/m²)Level
16.5Intense
26.5Intense
36.6Intense
46.6Intense
56.6Intense
66.7Intense
76.7Intense
86.7Intense
96.7Intense
106.7Intense
116.7Intense
126.8Intense
136.8Intense
146.8Intense
156.8Intense
166.8Intense
176.8Intense
186.9Intense
196.9Intense
206.9Intense
216.9Intense
227.0Intense
237.0Intense
247.0Intense
257.0Intense
267.1Intense
277.1Intense
287.1Intense
297.2Intense
307.2Intense
317.2Intense
Planning a trip in May

Is May a good time to visit Tri-Cities?

Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

7.6
Sightseeing
2nd-best month of the year
6.9
Beach & pool
5th-best month of the year

May is one of the better times to visit Tri-Cities for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Tri-Cities in May

From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In May, Tri-Cities sees daytime highs around 77°F and nights near 52°F. Pack sun protection. Worth having: light clothes. About 5 days see rain.

sun protectionlight clothes

UV index in Tri-Cities in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Tri-Cities peaks around July 16 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 17 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighHighVery highHighModerateLowJul 16UV 8Dec 17UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar4Moderate
Apr5Moderate
May7Very high
Jun6High
Jul8Very high
Aug6High
Sep5Moderate
Oct3Moderate
Nov1Low
Dec1Low

Air quality in Tri-Cities in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in Tri-Cities is worst in August — around 27 µg/m³ PM2.5 (moderate), about 3.1× the cleanest month (December, 9 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateGoodAug 2026 µg/m³Dec 189 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb11Good
Mar14Moderate
Apr11Good
May9Good
Jun10Good
Jul13Moderate
Aug27Moderate
Sep21Moderate
Oct12Moderate
Nov11Good
Dec9Good
Location & terrain

Where is Tri-Cities?

Tri-Cities sits at 46.2°N, 119.2°W, 348 ft above sea level, in United States. The nearest listed city is Kennewick, 3.7 mi away.

Topography around Tri-Cities

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Tri-Cities.

Within 2 miles, the terrain around Tri-Cities has only modest variations in elevation — a maximum elevation change of 197 ft around an average of 400 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,677 ft; within 50 miles, large variations in elevation — a maximum elevation change of 3,894 ft.

The land around Tri-Cities is covered by artificial surfaces (32%) and grassland (28%) within 2 miles, grassland (38%) and cropland (28%) within 10 miles, and grassland (51%) and cropland (42%) within 50 miles.

2 miles
197 ft
10 miles
1,677 ft
50 miles
3,894 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Kennewick 3.7 mi · Pasco 4.3 mi · Richland 5.0 mi · Hermiston 29 mi · Sunnyside 39 mi · Walla Walla 43 mi · Pendleton 44 mi · Moses Lake 62 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Tri-Cities (46.2454°, -119.1962°, elevation 348 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).