Climate averages 1991–2020
Tri-Cities weather
in May.
A warm, fairly dry month: the 5th warmest and the 6th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
May is a warm month in Tri-Cities: daytime highs average 25.0°C and nights cool to about 11.5°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 18 mm of rain on roughly 5 days, which makes May a fairly dry month (the 6th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 57 min on an average May day.
The nearest other city in this atlas is Kennewick (6 km away). In May its highs average 24.8°C, about as warm as Tri-Cities, with 18 mm of rain.
Among the 498 cities listed in the United States, Tri-Cities ranks joint 197th of 498 for the warmest May highs and joint 96th of 498 for the driest May (rainfall, lowest first). The mean May high of those 498 cities is 23.8°C; Tri-Cities is 1.2°C warmer than that mean.
From May to June, average highs rise by 3.9°C to 28.9°C, and monthly rainfall falls from 18 mm to 13 mm.
The annual picture
May in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Tri-Cities climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 6.0°C-1.5°C | -1.5°C | 34 | 8.1 | 9.19 h |
| February | 9.3°C-0.3°C | -0.3°C | 23 | 6.2 | 10.310 h |
| March | 14.3°C2.8°C | 2.8°C | 24 | 5.9 | 11.912 h |
| April | 19.3°C6.6°C | 6.6°C | 17 | 4.9 | 13.514 h |
| May, selected | 25.0°C11.5°C | 11.5°C | 18 | 4.5 | 15.015 h |
| June | 28.9°C15.3°C | 15.3°C | 13 | 2.8 | 15.716 h |
| July | 34.2°C19.2°C | 19.2°C | 3.8 | 1.0 | 15.415 h |
| August | 33.2°C18.6°C | 18.6°C | 4.2 | 1.0 | 14.214 h |
| September | 27.5°C14.0°C | 14.0°C | 6.9 | 1.8 | 12.613 h |
| October | 18.9°C7.9°C | 7.9°C | 22 | 5.0 | 11.011 h |
| November | 10.7°C2.3°C | 2.3°C | 29 | 7.3 | 9.59 h |
| December | 5.6°C-1.2°C | -1.2°C | 35 | 8.4 | 8.79 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
May in nearby cities
- Kennewick in MayUnited States · 6 kmHigh 24.8°C · Low 11.4°C · 18 mm rain
- Yakima in MayUnited States · 108 kmHigh 21.4°C · Low 7.8°C · 18 mm rain
- Spokane in MayUnited States · 207 kmHigh 19.9°C · Low 7.8°C · 46 mm rain
- Spokane Valley in MayUnited States · 217 kmHigh 19.2°C · Low 7.0°C · 51 mm rain
- Auburn in MayUnited States · 259 kmHigh 17.3°C · Low 8.0°C · 78 mm rain
- Kent in MayUnited States · 263 kmHigh 17.6°C · Low 8.4°C · 76 mm rain
- Gresham in MayUnited States · 264 kmHigh 17.8°C · Low 7.9°C · 89 mm rain
- Federal Way in MayUnited States · 266 kmHigh 16.7°C · Low 7.7°C · 78 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Tri-Cities) is explained once on the Tri-Cities year overview and on the Sources, method and limits page.
Kennewick lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.