Climate and average weather in Riom
In Riom, the summers are warm, showery, and partly cloudy and the winters are cold, snowy, and mostly cloudy.
Over the course of the year, the temperature in Riom typically varies from 0°C to 25°C, and is rarely below -5°C or above 32°C. July is the hottest month of the year, while January is the coldest.
Based on the travel score, the best time of year to visit Riom for warm-weather activities is from late May to late September.
- Hottest
- Jul
- 25°
- Coldest
- Jan
- 0°
- Wettest
- May
- 93 mm
- Driest
- Feb
- 48 mm
- Rain / yr
- 862 mm
- 141 wet days
- Daylight
- 8.5–15.5 h
- shortest–longest
- Elevation
- 362 m
- 45.9°N
- Clearest
- Aug
- 54% cloud
- Air quality
- Excellent
- PM10 13.5 µg/m³ · 2019
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Riom 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 late May to late September.
Temperature through the year
Daily average highs and lows in Riom, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 3.5 months, from June 2 to September 14, with daily high temperatures above 21°C. The hottest month of the year in Riom is July, with an average high of 25°C and low of 13°C.
The cool season lasts 3.6 months, from November 16 to March 4, with daily high temperatures below 10°C. The coldest month of the year in Riom is January, with an average low of 0°C and high of 7°C.
Days typically run about 9°C warmer than nights, with the widest day–night swing (around 12°C) in August.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 7 | 8 | 12 | 15 | 19 | 22 | 25 | 25 | 21 | 16 | 10 | 7 |
| Avg low (°C) | 0 | 0 | 2 | 5 | 8 | 12 | 13 | 13 | 10 | 7 | 3 | 1 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 7 | 0 |
| Feb | 8 | 0 |
| Mar | 12 | 2 |
| Apr | 15 | 5 |
| May | 19 | 8 |
| Jun | 22 | 12 |
| Jul | 25 | 13 |
| Aug | 25 | 13 |
| Sep | 21 | 10 |
| Oct | 16 | 7 |
| Nov | 10 | 3 |
| Dec | 7 | 1 |
How hot and cold Riom really feels
The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.
On the coldest nights, wind chill pulls the feels-like down to about -4°C (around February 2), with roughly 129 freezing days a year (feels-like at or below 0°C), worst in February.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°C) | 7 | 8 | 12 | 15 | 19 | 22 | 25 | 25 | 20 | 16 | 10 | 7 |
| Air high (°C) | 7 | 8 | 12 | 15 | 19 | 22 | 25 | 25 | 21 | 16 | 10 | 7 |
| Feels-like low (°C) | -3 | -3 | -1 | 2 | 7 | 12 | 13 | 13 | 9 | 5 | 0 | -2 |
| Air low (°C) | 0 | 0 | 2 | 5 | 8 | 12 | 13 | 13 | 10 | 7 | 3 | 1 |
| Feels-like high (°C) | Air high (°C) | Feels-like low (°C) | Air low (°C) | |
|---|---|---|---|---|
| Jan | 7 | 7 | -3 | 0 |
| Feb | 8 | 8 | -3 | 0 |
| Mar | 12 | 12 | -1 | 2 |
| Apr | 15 | 15 | 2 | 5 |
| May | 19 | 19 | 7 | 8 |
| Jun | 22 | 22 | 12 | 12 |
| Jul | 25 | 25 | 13 | 13 |
| Aug | 25 | 25 | 13 | 13 |
| Sep | 20 | 21 | 9 | 10 |
| Oct | 16 | 16 | 5 | 7 |
| Nov | 10 | 10 | 0 | 3 |
| Dec | 7 | 7 | -2 | 1 |
Average hourly temperature in Riom
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 July afternoons, near 25°C, and coldest before dawn in January, near 0°C.
Riom weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 7° / 0° | 59 | 12.4 | 3.5 | 8.9 | 0.7 |
| Feb | 8° / 0° | 48 | 11 | 3.3 | 10 | 1.2 |
| Mar | 12° / 2° | 54 | 11 | 1.2 | 11.6 | 3.0 |
| Apr | 15° / 5° | 79 | 13.1 | 0.6 | 13.3 | 4.1 |
| May | 19° / 8° | 93 | 14.1 | 0 | 14.7 | 5.3 |
| Jun | 22° / 12° | 79 | 11.9 | 0 | 15.5 | 6.3 |
| Jul | 25° / 13° | 84 | 10.5 | 0 | 15.2 | 6.9 |
| Aug | 25° / 13° | 85 | 10.9 | 0 | 14 | 6.9 |
| Sep | 21° / 10° | 79 | 10.2 | 0 | 12.3 | 6.3 |
| Oct | 16° / 7° | 72 | 11.2 | 0.2 | 10.7 | 4.8 |
| Nov | 10° / 3° | 72 | 12.7 | 1.2 | 9.3 | 2.2 |
| Dec | 7° / 1° | 61 | 12.3 | 2.5 | 8.5 | 0.9 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Riom gets about 862 mm of precipitation a year. On a typical day the chance of rain is often wet, but that rises and falls sharply with the seasons.
The wetter season lasts 2.6 months, from around Apr 1 to Jun 17, peaking in May at about 49% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Sep 2.
May is the wettest month by volume, with 93 mm over about 14 wet days; February is the driest, with 48 mm. Some of the cold-season precipitation falls as snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 40 | 40 | 35 | 43 | 46 | 40 | 34 | 34 | 35 | 36 | 41 | 40 |
| Rain days | 12 | 11 | 11 | 13 | 14 | 12 | 11 | 11 | 10 | 11 | 13 | 12 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 40 | 12 |
| Feb | 40 | 11 |
| Mar | 35 | 11 |
| Apr | 43 | 13 |
| May | 46 | 14 |
| Jun | 40 | 12 |
| Jul | 34 | 11 |
| Aug | 34 | 11 |
| Sep | 35 | 10 |
| Oct | 36 | 11 |
| Nov | 41 | 13 |
| Dec | 40 | 12 |
Monthly rainfall
Over a full year, Riom collects about 862 mm of rain across 141 wet days — roughly 72 mm in an average month.
It doesn’t fall evenly. May is the wettest month with 93 mm, while February is the driest at just 48 mm. The three wettest months alone bring about 30% of the year’s total, and some of the cold-season precipitation falls as snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 59 | 48 | 54 | 79 | 93 | 79 | 84 | 85 | 79 | 72 | 72 | 61 |
| Rain days | 12 | 11 | 11 | 13 | 14 | 12 | 11 | 11 | 10 | 11 | 13 | 12 |
| Snow days | 4 | 3 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 3 |
| Rainfall (mm) | Rain days | Snow days | |
|---|---|---|---|
| Jan | 59 | 12 | 4 |
| Feb | 48 | 11 | 3 |
| Mar | 54 | 11 | 1 |
| Apr | 79 | 13 | 1 |
| May | 93 | 14 | 0 |
| Jun | 79 | 12 | 0 |
| Jul | 84 | 11 | 0 |
| Aug | 85 | 11 | 0 |
| Sep | 79 | 10 | 0 |
| Oct | 72 | 11 | 0 |
| Nov | 72 | 13 | 1 |
| Dec | 61 | 12 | 3 |
Snow in Riom
Average snowy days through the year, the snow-season span, and estimated snowfall — for ski trips and the perennial 'will there be snow at Christmas?' question.
Riom averages about 12 snowy days a year. Snow season runs roughly Nov 9 to Apr 23 — about 5.5 months.
February is snowiest, with roughly 4 days of snow and an estimated 13 cm of snowfall. Over the year that adds up to an estimated 44 cm of snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Snow days | 4 | 3 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 3 |
| Snowfall (cm) | 12 | 13 | 3 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 5 | 9 |
| Snow days | Snowfall (cm) | |
|---|---|---|
| Jan | 4 | 12 |
| Feb | 3 | 13 |
| Mar | 1 | 3 |
| Apr | 1 | 2 |
| May | 0 | 0 |
| Jun | 0 | 0 |
| Jul | 0 | 0 |
| Aug | 0 | 0 |
| Sep | 0 | 0 |
| Oct | 0 | 0 |
| Nov | 1 | 5 |
| Dec | 3 | 9 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Riom, 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 June 11 and lasts for 3.5 months, ending around September 26. The clearest month is August, when the sky is clear, mostly clear, or partly cloudy 53% of the time on average.
The cloudier part of the year begins around September 27 and lasts for 5.3 months, ending around March 7. The cloudiest month is January, when it is overcast or mostly cloudy 71% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 29 | 33 | 38 | 36 | 34 | 41 | 50 | 53 | 43 | 34 | 29 | 30 |
| Cloudier (%) | 71 | 67 | 62 | 64 | 66 | 59 | 50 | 47 | 57 | 66 | 71 | 70 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 29 | 71 |
| Feb | 33 | 67 |
| Mar | 38 | 62 |
| Apr | 36 | 64 |
| May | 34 | 66 |
| Jun | 41 | 59 |
| Jul | 50 | 50 |
| Aug | 53 | 47 |
| Sep | 43 | 57 |
| Oct | 34 | 66 |
| Nov | 29 | 71 |
| Dec | 30 | 70 |
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 11, brings about 15 h 30 min of light; the shortest, around January 1, only 8 h 30 min — a swing of roughly 7 hours.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 8.9 | 10.0 | 11.6 | 13.3 | 14.7 | 15.5 | 15.2 | 14.0 | 12.3 | 10.7 | 9.3 | 8.5 |
| Sunrise (AM) | 8:32 | 8:00 | 7:09 | 6:09 | 5:22 | 5:02 | 5:17 | 5:53 | 6:32 | 7:12 | 7:56 | 8:29 |
| Sunset (PM) | 5:22 | 6:04 | 6:45 | 7:27 | 8:06 | 8:33 | 8:29 | 7:51 | 6:51 | 5:53 | 5:09 | 4:58 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 8.9 | 8:32 | 5:22 |
| Feb | 10.0 | 8:00 | 6:04 |
| Mar | 11.6 | 7:09 | 6:45 |
| Apr | 13.3 | 6:09 | 7:27 |
| May | 14.7 | 5:22 | 8:06 |
| Jun | 15.5 | 5:02 | 8:33 |
| Jul | 15.2 | 5:17 | 8:29 |
| Aug | 14.0 | 5:53 | 7:51 |
| Sep | 12.3 | 6:32 | 6:51 |
| Oct | 10.7 | 7:12 | 5:53 |
| Nov | 9.3 | 7:56 | 5:09 |
| Dec | 8.5 | 8:29 | 4:58 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Riom averages about 7 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 5 and 10 days.
The sunnier stretch runs 3.4 months, from around Jun 14 to Sep 25. The sunniest month is July, with roughly 10 sunny days (mixed).
The greyest month is May, down near 6 sunny days — about 41% fewer than the July peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 6 | 6 | 8 | 7 | 6 | 7 | 10 | 10 | 8 | 6 | 5 | 5 |
| Sky | Gloomy | Gloomy | Mixed | Gloomy | Gloomy | Gloomy | Mixed | Mixed | Mixed | Gloomy | Gloomy | Gloomy |
| Sunny days | Sky | |
|---|---|---|
| Jan | 6 | Gloomy |
| Feb | 6 | Gloomy |
| Mar | 8 | Mixed |
| Apr | 7 | Gloomy |
| May | 6 | Gloomy |
| Jun | 7 | Gloomy |
| Jul | 10 | Mixed |
| Aug | 10 | Mixed |
| Sep | 8 | Mixed |
| Oct | 6 | Gloomy |
| Nov | 5 | Gloomy |
| Dec | 5 | Gloomy |
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 Riom, how humid it feels changes noticeably over the year.
The more humid part of the year lasts 3.3 months, from around June 3 to September 10. The muggiest month is August, when the air feels humid, muggy or worse about 16% of the time.
The most comfortable stretch runs from around September 11 to June 2, and October is the most comfortable month — the air is dry or comfortable 100% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 100 | 100 | 100 | 100 | 92 | 65 | 48 | 47 | 78 | 94 | 100 | 100 |
| Comfortable (%) | 0 | 0 | 0 | 0 | 7 | 24 | 36 | 36 | 19 | 6 | 0 | 0 |
| Humid (%) | 0 | 0 | 0 | 0 | 1 | 10 | 15 | 15 | 3 | 0 | 0 | 0 |
| Muggy (%) | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | |
|---|---|---|---|---|
| Jan | 100 | 0 | 0 | 0 |
| Feb | 100 | 0 | 0 | 0 |
| Mar | 100 | 0 | 0 | 0 |
| Apr | 100 | 0 | 0 | 0 |
| May | 92 | 7 | 1 | 0 |
| Jun | 65 | 24 | 10 | 1 |
| Jul | 48 | 36 | 15 | 1 |
| Aug | 47 | 36 | 15 | 1 |
| Sep | 78 | 19 | 3 | 0 |
| Oct | 94 | 6 | 0 | 0 |
| Nov | 100 | 0 | 0 | 0 |
| Dec | 100 | 0 | 0 | 0 |
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 Riom is typically calm, near 10 km/h, and varies little with the seasons.
The windier part of the year lasts 6.6 months, from around Oct 16 to May 4. The windiest month is December, averaging about 11 km/h (calm).
The calmer part of the year runs from around May 5 to Oct 15, with August the calmest month at about 8 km/h.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 11 | 11 | 11 | 10 | 10 | 9 | 8 | 8 | 9 | 10 | 11 | 11 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 11 | calm |
| Feb | 11 | calm |
| Mar | 11 | calm |
| Apr | 10 | calm |
| May | 10 | calm |
| Jun | 9 | calm |
| Jul | 8 | calm |
| Aug | 8 | calm |
| Sep | 9 | calm |
| Oct | 10 | calm |
| Nov | 11 | calm |
| Dec | 11 | calm |
Best time to visit Riom
To characterize how pleasant the weather is in Riom throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around late September, Riom 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 18°C and 28°C. Based on this score, the best time of year to visit Riom for general outdoor tourist activities is from late May to late September, with a peak score in the last week of August.
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) | 0.7 | 1.2 | 3.0 | 4.1 | 5.3 | 6.3 | 6.9 | 6.9 | 6.3 | 4.7 | 2.3 | 0.9 |
| Rating | poor | poor | poor | fair | fair | good | good | good | good | fair | poor | poor |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 0.7 | poor |
| Feb | 1.2 | poor |
| Mar | 3.0 | poor |
| Apr | 4.1 | fair |
| May | 5.3 | fair |
| Jun | 6.3 | good |
| Jul | 6.9 | good |
| Aug | 6.9 | good |
| Sep | 6.3 | good |
| Oct | 4.7 | fair |
| Nov | 2.3 | poor |
| Dec | 0.9 | poor |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best time of year to visit Riom for hot-weather activities is from late June to early September, with a peak score in the last week of July.
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 Riom, 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.
For a warm-season trip around July (highs near 25°C), the essentials are light clothes, rain gear and sun protection. In the cold season around January (highs near 7°C), pack a warm layer, a heavy coat and rain gear.
In July, Riom sees daytime highs around 25°C and nights near 13°C. Worth packing: light clothes, rain gear and sun protection. About 11 days see rain.
UV index (midday) in Riom 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 Riom peaks around July 15 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 2 | 4 | 6 | 7 | 7 | 8 | 7 | 5 | 3 | 2 | 1 |
| Level | Low | Moderate | Moderate | High | High | Very high | Very high | High | Moderate | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 2 | Moderate |
| Mar | 4 | Moderate |
| Apr | 6 | High |
| May | 7 | High |
| Jun | 7 | Very high |
| Jul | 8 | Very high |
| Aug | 7 | High |
| Sep | 5 | Moderate |
| Oct | 3 | Moderate |
| Nov | 2 | Low |
| Dec | 1 | Low |
Average hourly UV index in Riom
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 July the burn window is concentrated in the middle of the day: about 8 hours a day reach index 3 (protection recommended), and 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) | 0 | 0 | 4 | 6 | 7.5 | 8 | 8 | 7 | 5 | 1 | 0 | 0 |
| UV ≥ 6 (h/day) | 0 | 0 | 0 | 0 | 3 | 4 | 5 | 3 | 0 | 0 | 0 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 0 | 0 |
| Feb | 0 | 0 |
| Mar | 4 | 0 |
| Apr | 6 | 0 |
| May | 7.5 | 3 |
| Jun | 8 | 4 |
| Jul | 8 | 5 |
| Aug | 7 | 3 |
| Sep | 5 | 0 |
| Oct | 1 | 0 |
| Nov | 0 | 0 |
| Dec | 0 | 0 |
Growing season
The growing season in Riom typically lasts about 342 days, from around February 15 to January 22 — the span where a frost-free day is more likely than not. It is reliably frost-free from April 16 to October 30.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 52 | 51 | 73 | 90 | 99 | 100 | 100 | 100 | 100 | 96 | 78 | 60 |
| Frost nights | 31 | 28 | 31 | 16 | 0 | 0 | 0 | 0 | 0 | 2 | 30 | 31 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 52 | 31 |
| Feb | 51 | 28 |
| Mar | 73 | 31 |
| Apr | 90 | 16 |
| May | 99 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 96 | 2 |
| Nov | 78 | 30 |
| Dec | 60 | 31 |
Growing degree days
Growing degree days tally heat above 10°C: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Riom banks about 1,083 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around July.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 0 | 0 | 0 | 9 | 106 | 209 | 280 | 274 | 155 | 51 | 0 | 0 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 0 |
| Feb | 0 |
| Mar | 0 |
| Apr | 9 |
| May | 106 |
| Jun | 209 |
| Jul | 280 |
| Aug | 274 |
| Sep | 155 |
| Oct | 51 |
| Nov | 0 |
| Dec | 0 |
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.
Riom receives about 3.6 kWh/m² a day of solar energy on average — moderate — with a clear seasonal swing between 1.1 and 6.0 kWh/m².
The brighter stretch of the year lasts 6.1 months, from around Mar 18 to Sep 20. The brightest month is June, averaging about 5.8 kWh/m² (bright).
The dimmest month is December, down near 1.1 kWh/m² — roughly 81% less than the June peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 1.3 | 2.2 | 3.5 | 4.7 | 5.3 | 5.8 | 5.9 | 5.2 | 3.9 | 2.5 | 1.5 | 1.1 |
| Level | Dim | Moderate | Moderate | Bright | Bright | Bright | Bright | Bright | Moderate | Moderate | Dim | Dim |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 1.3 | Dim |
| Feb | 2.2 | Moderate |
| Mar | 3.5 | Moderate |
| Apr | 4.7 | Bright |
| May | 5.3 | Bright |
| Jun | 5.8 | Bright |
| Jul | 5.9 | Bright |
| Aug | 5.2 | Bright |
| Sep | 3.9 | Moderate |
| Oct | 2.5 | Moderate |
| Nov | 1.5 | Dim |
| Dec | 1.1 | Dim |
Where is Riom?
Riom sits at 45.9°N, 3.1°E, 362 m above sea level, in France. The nearest listed city is Clermont-Ferrand, 13 km away.
Topography around Riom
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Riom.
Within 3 km, the terrain around Riom has only modest variations in elevation — a maximum elevation change of 196 m around an average of 350 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 907 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,675 m.
The land around Riom is covered by cropland (32%), artificial surfaces (27%) and trees (22%) within 3 km, cropland (39%), trees (28%) and grassland (22%) within 16 km, and grassland (46%) and trees (38%) within 80 km.
France travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type C / E
- 230 V · 50 Hz
- Prices
- ≈ 77% of US
- price level, 2025
- GDP per capita
- $48,986
- 2025
- Happiness
- 6.6 / 10
- World Happiness, 2025
- Safe drinking water
- 100%
- of population, 2024
- Homicide rate
- 1.3
- per 100k, 2023
- Road deaths
- 5.1
- per 100k/yr, 2019
- Income group
- High
- World Bank
- English
- Moderate
- EF EPI 539
- 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 Riom (45.8936°, 3.1126°, elevation 362 m), 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).