Hillsboro, OR weather in May
Expect mild weather with frequent rain in Hillsboro in May, with highs near 68°F and lows near 45°F. Rain falls on about 12 days. Great for outdoor plans.
- Normal high
- 68°F
- Normal low
- 45°F
- Wet days
- 12
- 2.1 in total
- Muggy days
- 0
- dew point 65°F+
How May changes from start to finish
| May 1 | May 31 | |
|---|---|---|
| Normal high | 64°F | 71°F |
| Normal low | 42°F | 48°F |
| Chance of a wet day | 42% | 34% |
| Sunrise / sunset | 5:59 am / 8:18 pm | 5:27 am / 8:52 pm |
| Daylight | 14.3 h | 15.4 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Pacific Time).
A typical May day
- 6 am49°Fdew point 46°F
- 9 am57°Fdew point 47°F
- Noon63°Fdew point 47°F
- 3 pm66°Fdew point 47°F
- 6 pm64°Fdew point 47°F
- 9 pm56°Fdew point 47°F
NOAA hourly normals (local standard time) from Portland-Hillsboro Airport (2 mi away); average wind 5 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F15 of 31
- Hot dayshigh 90°F or more1 of 31
- Muggy daysdaily mean dew point 65°F or more0 of 31
- Wet daysat least 0.01 in of rain or melted snow12 of 31
- Notable rainat least 0.10 in6 of 31
- Freezing nightslow 32°F or below0 of 31
- Snow on the groundsnow depth 1 in or more0 of 31
Average days per May, counted from daily records for each year 1991-2020.
Rain in May
Normal precipitation is 2.1 in; a dry May brings about 1.2 in and a wet one about 2.7 in (25th and 75th percentiles). About 1 day brings half an inch or more.
How May varies from year to year
- Warmest May, 1991-20201992: average high 79°F
- Coolest May2011: average high 61°F
- Wettest May1996: 4.8 in
- Driest May2018: 0.06 in
- Highest reading99°F (May 25, 2001)
- Lowest reading30°F (May 18, 2003)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
May compared with April and June
| April | May | June | |
|---|---|---|---|
| Normal high | 60°F | 68°F | 73°F |
| Normal low | 39°F | 45°F | 50°F |
| Wet days | 16 | 12 | 8 |
| Comfortable days | 8 | 15 | 18 |
| Daylight | 13.5 h | 14.9 h | 15.6 h |
Highs change by +8°F from April and +5°F into June.
Nearby alternatives in May
- Drier: Bend, OR130 mi · high 66°F · 6 wet days
- Cooler: Cannon Beach, OR53 mi · high 61°F · 14 wet days
How Hillsboro ranks in May
- Normal high301st warmest of 378 cities; 3rd of 6 in Oregon
- Wet days248th driest of 378
- Comfortable days116th most of 339
What to pack for Hillsboro in May
- A rain jacket or umbrella – rain on about 12 days
Heating and cooling
May has 273 heating degree days and 16 cooling degree days (base 65°F), 5% of the year's total heating and cooling demand.
Questions
How cold is Hillsboro in May?
The normal high is 68°F and the normal low is 45°F. From 1991 to 2020 the coldest May reading was 30°F (May 18, 2003).
Does it rain a lot in Hillsboro in May?
About 12 days in May have at least 0.01 in of precipitation, and the normal total is 2.1 in. The wettest May in 1991-2020 was in 1996 (4.8 in); the driest was in 2018 (0.06 in).
Is May a good time to visit Hillsboro?
May ranks 2nd of 12 months on our comfort score for Hillsboro (73 out of 100). It has about 15 comfortable days and about 1 day at 90°F or hotter. The best month is June.
Where the numbers come from
- Temperature and snow depth: Forest Grove (USC00352997), 5.5 mi W of the city center, 180 ft . NOAA normals and daily records, 1991-2020.
- Rain and snowfall: Dilley 2 S (USC00352325), 7.3 mi SW of the city center, 194 ft . NOAA normals and daily records, 1991-2020.
- Frost dates and humidity and wind by hour: Portland-Hillsboro Airport (USW00094261), 2.3 mi ENE of the city center, 204 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Portland International Airport (726980-24229), 19 mi ENE of the city center, 22 ft (173 ft lower than the city). Hourly observations, 1991-2020.
- Not available for this location: cloud cover (no station close enough or similar enough in elevation).