Climate and average weather in Hilo
In Hilo, the weather is humid, warm, wet, and mostly clear and remarkably steady, with daytime highs holding near warm levels all year. The wettest stretch peaks around March.
Over the course of the year, the temperature in Hilo typically varies from 67°F to 77°F, and is rarely below 65°F or above 80°F. September is the hottest month of the year, while February is the coldest.
Based on the travel score, the best times of year to visit Hilo for warm-weather activities are from early January to mid March and late August to late October.
- Hottest
- Sep
- 77°
- Coldest
- Feb
- 67°
- Wettest
- Mar
- 9.1 in
- Driest
- Sep
- 4.5 in
- Rain / yr
- 76.6 in
- 272 wet days
- Daylight
- 10.8–13.2 h
- shortest–longest
- Elevation
- 59 ft
- 19.7°N
- Clearest
- Jan
- 48% cloud
Hilo is human settlement and census-designated place in Hawaii, United States.
- Density
- 287/km²
- people per km²
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Hilo weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around early January to mid March.
Temperature through the year
Daily average highs and lows in Hilo, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
Temperatures in Hilo stay fairly even through the year, without a distinct hot or cool season. The warmest month is September, with an average high of 77°F and low of 72°F; the coolest is February, with an average low of 67°F and high of 72°F.
Days typically run about 5°F warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 73 | 72 | 72 | 73 | 74 | 75 | 76 | 77 | 77 | 77 | 75 | 73 |
| Avg low (°F) | 67 | 67 | 67 | 68 | 69 | 70 | 71 | 72 | 72 | 71 | 70 | 68 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| Jan | 73 | 67 |
| Feb | 72 | 67 |
| Mar | 72 | 67 |
| Apr | 73 | 68 |
| May | 74 | 69 |
| Jun | 75 | 70 |
| Jul | 76 | 71 |
| Aug | 77 | 72 |
| Sep | 77 | 72 |
| Oct | 77 | 71 |
| Nov | 75 | 70 |
| Dec | 73 | 68 |
Average hourly temperature in Hilo
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on September afternoons, near 77°F, and coldest before dawn in February, near 67°F.
Hilo weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 73° / 67° | 5.8 | 16.8 | 10.9 | 6.0 |
| Feb | 72° / 67° | 6.6 | 17.2 | 11.3 | 5.5 |
| Mar | 72° / 67° | 9.1 | 23.5 | 11.9 | 4.7 |
| Apr | 73° / 68° | 7.1 | 24.8 | 12.4 | 4.5 |
| May | 74° / 69° | 5.7 | 23.7 | 12.9 | 4.9 |
| Jun | 75° / 70° | 4.7 | 24.1 | 13.2 | 4.8 |
| Jul | 76° / 71° | 5.7 | 25.8 | 13.1 | 4.6 |
| Aug | 77° / 72° | 6.7 | 25.6 | 12.7 | 4.6 |
| Sep | 77° / 72° | 4.5 | 22 | 12.1 | 5.1 |
| Oct | 77° / 71° | 5.4 | 23 | 11.5 | 5.0 |
| Nov | 75° / 70° | 7.5 | 23.2 | 11.1 | 4.8 |
| Dec | 73° / 68° | 7.9 | 22.2 | 10.8 | 5.1 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Hilo gets about 76.6 in of precipitation a year. On a typical day the chance of rain is very wet, but that rises and falls sharply with the seasons.
The wetter season lasts 5.7 months, from around Mar 14 to Sep 1, peaking in August at about 86% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Jan 12.
March is the wettest month by volume, with 9.1 in over about 24 wet days; September is the driest, with 4.5 in.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 55 | 62 | 76 | 82 | 77 | 80 | 83 | 82 | 74 | 74 | 77 | 71 |
| Rain days | 17 | 17 | 24 | 25 | 24 | 24 | 26 | 26 | 22 | 23 | 23 | 22 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 55 | 17 |
| Feb | 62 | 17 |
| Mar | 76 | 24 |
| Apr | 82 | 25 |
| May | 77 | 24 |
| Jun | 80 | 24 |
| Jul | 83 | 26 |
| Aug | 82 | 26 |
| Sep | 74 | 22 |
| Oct | 74 | 23 |
| Nov | 77 | 23 |
| Dec | 71 | 22 |
Monthly rainfall
Over a full year, Hilo collects about 76.6 in of rain across 272 wet days — roughly 6.4 in in an average month.
It doesn’t fall evenly. March is the wettest month with 9.1 in, while September is the driest at just 4.5 in. The three wettest months alone bring about 32% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (in) | 5.8 | 6.6 | 9.1 | 7.1 | 5.7 | 4.7 | 5.7 | 6.7 | 4.5 | 5.4 | 7.5 | 7.9 |
| Rain days | 17 | 17 | 24 | 25 | 24 | 24 | 26 | 26 | 22 | 23 | 23 | 22 |
| Rainfall (in) | Rain days | |
|---|---|---|
| Jan | 5.8 | 17 |
| Feb | 6.6 | 17 |
| Mar | 9.1 | 24 |
| Apr | 7.1 | 25 |
| May | 5.7 | 24 |
| Jun | 4.7 | 24 |
| Jul | 5.7 | 26 |
| Aug | 6.7 | 26 |
| Sep | 4.5 | 22 |
| Oct | 5.4 | 23 |
| Nov | 7.5 | 23 |
| Dec | 7.9 | 22 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Hilo, the average share of the sky covered by clouds shows moderate seasonal variation over the course of the year.
The clearer part of the year begins around December 17 and lasts for 2.0 months, ending around February 15. The clearest month is January, when the sky is clear, mostly clear, or partly cloudy 69% of the time on average.
The cloudier part of the year begins around October 6 and lasts for 2.4 months, ending around December 16. The cloudiest month is November, when it is overcast or mostly cloudy 51% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 69 | 61 | 50 | 50 | 58 | 64 | 65 | 67 | 69 | 55 | 49 | 59 |
| Cloudier (%) | 31 | 39 | 50 | 50 | 42 | 36 | 35 | 33 | 31 | 45 | 51 | 41 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 69 | 31 |
| Feb | 61 | 39 |
| Mar | 50 | 50 |
| Apr | 50 | 50 |
| May | 58 | 42 |
| Jun | 64 | 36 |
| Jul | 65 | 35 |
| Aug | 67 | 33 |
| Sep | 69 | 31 |
| Oct | 55 | 45 |
| Nov | 49 | 51 |
| Dec | 59 | 41 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around June 8, brings about 13 h 12 min of light; the shortest, around January 1, only 10 h 48 min — a swing of roughly 2 h 24 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 10.9 | 11.3 | 11.9 | 12.4 | 12.9 | 13.2 | 13.1 | 12.7 | 12.1 | 11.5 | 11.1 | 10.8 |
| Sunrise (AM) | 7:02 | 6:55 | 6:34 | 6:07 | 5:49 | 5:45 | 5:53 | 6:04 | 6:11 | 6:19 | 6:34 | 6:52 |
| Sunset (PM) | 5:57 | 6:15 | 6:26 | 6:34 | 6:45 | 6:56 | 6:59 | 6:45 | 6:18 | 5:52 | 5:37 | 5:41 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 10.9 | 7:02 | 5:57 |
| Feb | 11.3 | 6:55 | 6:15 |
| Mar | 11.9 | 6:34 | 6:26 |
| Apr | 12.4 | 6:07 | 6:34 |
| May | 12.9 | 5:49 | 6:45 |
| Jun | 13.2 | 5:45 | 6:56 |
| Jul | 13.1 | 5:53 | 6:59 |
| Aug | 12.7 | 6:04 | 6:45 |
| Sep | 12.1 | 6:11 | 6:18 |
| Oct | 11.5 | 6:19 | 5:52 |
| Nov | 11.1 | 6:34 | 5:37 |
| Dec | 10.8 | 6:52 | 5:41 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Hilo averages about 9 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 6 and 13 days.
The sunnier stretch runs 2.6 months, from around Dec 16 to Mar 5. The sunniest month is January, with roughly 13 sunny days (mixed).
The greyest month is March, down near 7 sunny days — about 42% fewer than the January peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 13 | 10 | 7 | 6 | 8 | 8 | 9 | 9 | 11 | 7 | 7 | 9 |
| Sky | Mixed | Mixed | Gloomy | Gloomy | Gloomy | Mixed | Mixed | Mixed | Mixed | Gloomy | Gloomy | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 13 | Mixed |
| Feb | 10 | Mixed |
| Mar | 7 | Gloomy |
| Apr | 6 | Gloomy |
| May | 8 | Gloomy |
| Jun | 8 | Mixed |
| Jul | 9 | Mixed |
| Aug | 9 | Mixed |
| Sep | 11 | Mixed |
| Oct | 7 | Gloomy |
| Nov | 7 | Gloomy |
| Dec | 9 | Mixed |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
In Hilo, how humid it feels changes noticeably over the year.
The more humid part of the year lasts 7.7 months, from around April 19 to December 7. The muggiest month is May, when the air feels humid, muggy or worse about 99% of the time.
The most comfortable stretch runs from around December 8 to April 18, and February is the most comfortable month — the air is dry or comfortable 22% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 1 | 2 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Comfortable (%) | 14 | 20 | 12 | 6 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 6 |
| Humid (%) | 56 | 52 | 59 | 57 | 42 | 19 | 8 | 5 | 6 | 8 | 25 | 49 |
| Muggy (%) | 29 | 26 | 28 | 37 | 56 | 80 | 78 | 73 | 73 | 76 | 67 | 44 |
| Oppressive (%) | 0 | 0 | 0 | 0 | 1 | 1 | 14 | 23 | 21 | 16 | 6 | 1 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | |
|---|---|---|---|---|---|
| Jan | 1 | 14 | 56 | 29 | 0 |
| Feb | 2 | 20 | 52 | 26 | 0 |
| Mar | 1 | 12 | 59 | 28 | 0 |
| Apr | 0 | 6 | 57 | 37 | 0 |
| May | 0 | 1 | 42 | 56 | 1 |
| Jun | 0 | 0 | 19 | 80 | 1 |
| Jul | 0 | 0 | 8 | 78 | 14 |
| Aug | 0 | 0 | 5 | 73 | 23 |
| Sep | 0 | 0 | 6 | 73 | 21 |
| Oct | 0 | 0 | 8 | 76 | 16 |
| Nov | 0 | 1 | 25 | 67 | 6 |
| Dec | 0 | 6 | 49 | 44 | 1 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Across the year, average wind speed in Hilo is typically calm, near 6 mph, and varies little with the seasons.
The windier part of the year lasts 6.0 months, from around Nov 16 to May 16. The windiest month is February, averaging about 8 mph (light breeze).
The calmer part of the year runs from around May 17 to Nov 15, with September the calmest month at about 5 mph.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 7 | 8 | 7 | 7 | 6 | 6 | 6 | 6 | 5 | 6 | 6 | 7 |
| Feels | calm | light breeze | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (mph) | Feels | |
|---|---|---|
| Jan | 7 | calm |
| Feb | 8 | light breeze |
| Mar | 7 | calm |
| Apr | 7 | calm |
| May | 6 | calm |
| Jun | 6 | calm |
| Jul | 6 | calm |
| Aug | 6 | calm |
| Sep | 5 | calm |
| Oct | 6 | calm |
| Nov | 6 | calm |
| Dec | 7 | calm |
Hazard calendar for Hilo
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Hilo sits in the eastern Pacific hurricane zone; the season peaks August–September.
Best time to visit Hilo
To characterize how pleasant the weather is in Hilo throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around early March, Hilo is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 64°F and 82°F. Based on this score, the best times of year to visit Hilo for general outdoor tourist activities run from late August to late October and again from early November to mid March, with a peak score in the second week of January.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 5.9 | 5.5 | 4.7 | 4.5 | 4.9 | 4.8 | 4.6 | 4.6 | 5.1 | 5.0 | 4.8 | 5.1 |
| Rating | good | fair | fair | fair | fair | fair | fair | fair | fair | fair | fair | fair |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 5.9 | good |
| Feb | 5.5 | fair |
| Mar | 4.7 | fair |
| Apr | 4.5 | fair |
| May | 4.9 | fair |
| Jun | 4.8 | fair |
| Jul | 4.6 | fair |
| Aug | 4.6 | fair |
| Sep | 5.1 | fair |
| Oct | 5.0 | fair |
| Nov | 4.8 | fair |
| Dec | 5.1 | fair |
The beach/pool score favors clear, rainless days with daytime highs between 75°F and 93°F. Based on this score, the best time of year to visit Hilo for hot-weather activities is from early May to late February, with a peak score in the first week of October.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Hilo, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
Hilo packs about the same all year — highs hold near 77°F. Across the year the things worth having are light clothes, rain gear and sun protection.
In September, Hilo sees daytime highs around 77°F and nights near 72°F. Pack rain gear and sun protection. Worth having: light clothes. About 22 days see rain.
Sea temperature near Hilo
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea at the nearest coast (about 11 mi away) is warmest in September at about 80°F and coldest in March near 75°F.
The water stays above 68°F all year — warm enough for a swim any month.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 76 | 75 | 75 | 76 | 77 | 78 | 79 | 79 | 80 | 80 | 78 | 77 |
| Comfort | Warm | Warm | Warm | Warm | Warm | Warm | Warm | Warm | Warm | Warm | Warm | Warm |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 76 | Warm |
| Feb | 75 | Warm |
| Mar | 75 | Warm |
| Apr | 76 | Warm |
| May | 77 | Warm |
| Jun | 78 | Warm |
| Jul | 79 | Warm |
| Aug | 79 | Warm |
| Sep | 80 | Warm |
| Oct | 80 | Warm |
| Nov | 78 | Warm |
| Dec | 77 | Warm |
UV index (midday) in Hilo by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Hilo peaks around August 15 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 7 (high).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 8 | 10 | 12 | 14 | 11 | 13 | 13 | 14 | 13 | 10 | 8 | 7 |
| Level | Very high | Very high | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Very high | High |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 8 | Very high |
| Feb | 10 | Very high |
| Mar | 12 | Extreme |
| Apr | 14 | Extreme |
| May | 11 | Extreme |
| Jun | 13 | Extreme |
| Jul | 13 | Extreme |
| Aug | 14 | Extreme |
| Sep | 13 | Extreme |
| Oct | 10 | Extreme |
| Nov | 8 | Very high |
| Dec | 7 | High |
Average hourly UV index in Hilo
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in August the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 6.5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 6.5 | 7 | 8 | 8.5 | 8.5 | 8.5 | 8.5 | 8.5 | 8 | 7 | 6 | 6 |
| UV ≥ 6 (h/day) | 3.5 | 5 | 6 | 6.5 | 6 | 6.5 | 6.5 | 6.5 | 6 | 5 | 3.5 | 2.5 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 6.5 | 3.5 |
| Feb | 7 | 5 |
| Mar | 8 | 6 |
| Apr | 8.5 | 6.5 |
| May | 8.5 | 6 |
| Jun | 8.5 | 6.5 |
| Jul | 8.5 | 6.5 |
| Aug | 8.5 | 6.5 |
| Sep | 8 | 6 |
| Oct | 7 | 5 |
| Nov | 6 | 3.5 |
| Dec | 6 | 2.5 |
Air quality in Hilo by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.
Air quality in Hilo is worst in January — around 28 µg/m³ PM2.5 (moderate), about 1.7× the cleanest month (July, 16 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 28 | 27 | 26 | 23 | 22 | 19 | 16 | 18 | 21 | 25 | 22 | 24 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 28 | Moderate |
| Feb | 27 | Moderate |
| Mar | 26 | Moderate |
| Apr | 23 | Moderate |
| May | 22 | Moderate |
| Jun | 19 | Moderate |
| Jul | 16 | Moderate |
| Aug | 18 | Moderate |
| Sep | 21 | Moderate |
| Oct | 25 | Moderate |
| Nov | 22 | Moderate |
| Dec | 24 | Moderate |
Growing season
Hilo is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| Frost nights | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 100 | 0 |
| Feb | 100 | 0 |
| Mar | 100 | 0 |
| Apr | 100 | 0 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 100 | 0 |
| Nov | 100 | 0 |
| Dec | 100 | 0 |
Growing degree days
Growing degree days tally heat above 50°F: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Hilo banks about 8,043 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around September.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°F·days) | 622 | 549 | 613 | 612 | 673 | 682 | 735 | 758 | 735 | 744 | 674 | 646 |
| Growing degree days (°F·days) | |
|---|---|
| Jan | 622 |
| Feb | 549 |
| Mar | 613 |
| Apr | 612 |
| May | 673 |
| Jun | 682 |
| Jul | 735 |
| Aug | 758 |
| Sep | 735 |
| Oct | 744 |
| Nov | 674 |
| Dec | 646 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Hilo receives about 5.6 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 4.0 and 6.7 kWh/m².
The brighter stretch of the year lasts 6.5 months, from around Mar 23 to Oct 5. The brightest month is June, averaging about 6.7 kWh/m² (intense).
The dimmest month is December, down near 4.1 kWh/m² — roughly 38% less than the June peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 4.3 | 4.9 | 5.4 | 6.2 | 6.5 | 6.7 | 6.6 | 6.4 | 6.0 | 5.2 | 4.3 | 4.2 |
| Level | Bright | Bright | Bright | Intense | Intense | Intense | Intense | Intense | Intense | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 4.3 | Bright |
| Feb | 4.9 | Bright |
| Mar | 5.4 | Bright |
| Apr | 6.2 | Intense |
| May | 6.5 | Intense |
| Jun | 6.7 | Intense |
| Jul | 6.6 | Intense |
| Aug | 6.4 | Intense |
| Sep | 6.0 | Intense |
| Oct | 5.2 | Bright |
| Nov | 4.3 | Bright |
| Dec | 4.2 | Bright |
Where is Hilo?
Hilo sits at 19.7°N, 155.1°W, 59 ft above sea level, in United States. The nearest listed city is Kīhei, 113 mi away.
Topography around Hilo
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Hilo.
Within 2 miles, the terrain around Hilo has only modest variations in elevation — a maximum elevation change of 774 ft around an average of 197 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,606 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 13,750 ft.
The land around Hilo is covered by trees (34%), water (29%) and grassland (22%) within 2 miles, trees (42%) and water (29%) within 10 miles, and water (49%) and grassland (20%) within 50 miles.
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
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 Hilo (19.7299°, -155.0907°, elevation 59 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).