Guaynabo in Fall
In fall (September, October and November), Guaynabo sees average daytime highs around 29°C and overnight lows near 24°C, with 447 mm of rain over about 72 wet days across the season. It is the 2nd-warmest season and the wettest season of the year.
Over the season highs ease from about 30°C in early September to 27°C by late November. The sky is clear or mostly clear about 21% of the time across fall, and the air most often feels oppressive.
Fall is Guaynabo's 3rd-best season to visit on our travel score. Guaynabo has little temperature swing across the year, so its calendar seasons blur — the season framing matters less here than for a place with four distinct seasons. For the whole year in context, see Guaynabo's year-round climate.
- Avg daytime high
- 29°C
- 2nd-warmest season
- Avg overnight low
- 24°C
- Rainfall
- 447 mm
- 72 wet days
- Avg wind
- 9 km/h
- Travel score
- 3.8
- 3rd-best season
- Months
- Sep · Oct · Nov
Temperature in Guaynabo in Fall
Over the season highs ease from about 30°C in early September to 27°C by late November.
A typical fall day in Guaynabo reaches about 29°C and drops to 24°C overnight. The warmest of the three months is September, the coolest November.
How fall really feels in Guaynabo
Once humidity and wind are folded in, fall brings about 62 days that feel above 32°C and 0 that feel at or below 0°C.
The story in fall is heat — humidity pushes the afternoon "feels like" well above the raw temperature.
Guaynabo weather by month
How the three fall months (September, October and November) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 26° / 22° | 49 | 15.7 | 11 | 6.0 |
| Feb | 27° / 21° | 39 | 13 | 11.4 | 6.2 |
| Mar | 27° / 22° | 55 | 14.8 | 11.9 | 6.0 |
| Apr | 28° / 22° | 87 | 17.7 | 12.4 | 5.3 |
| May | 28° / 23° | 142 | 21.9 | 12.9 | 4.2 |
| Jun | 29° / 24° | 99 | 20.8 | 13.1 | 4.0 |
| Jul | 29° / 24° | 110 | 21.8 | 13 | 3.9 |
| Aug | 30° / 25° | 127 | 24 | 12.6 | 3.6 |
| Sep | 29° / 24° | 168 | 25.2 | 12.1 | 3.4 |
| Oct | 29° / 24° | 156 | 24.9 | 11.6 | 3.6 |
| Nov | 28° / 23° | 124 | 22.3 | 11.1 | 4.5 |
| Dec | 27° / 22° | 59 | 16.5 | 10.9 | 5.8 |
Cloud cover in Fall
The sky is clear or mostly clear about 21% of the time across fall.
Chance of precipitation in Fall
Guaynabo gets around 447 mm of rain over 72 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 9 km/h across fall.
Sunrise & sunset in Fall
Daylight runs from about 12 h 24 min in early September to 11 hours by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 5.2 kWh/m².
Hazard calendar for Guaynabo
In fall, Guaynabo overlaps its atlantic hurricane season. The full year is below, with each hazard's peak months called out.
Guaynabo sits in the Atlantic hurricane belt; the season peaks August–October.
Guaynabo sees seasonal dust haze (July), heaviest in July.
Is fall a good time to visit Guaynabo?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a weaker month for outdoor sightseeing in Guaynabo.
What to pack for Guaynabo in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, Guaynabo sees daytime highs around 29°C and nights near 24°C. Pack light clothes and rain gear. Worth having: sun protection. About 72 days see rain.
Sea temperature near Guaynabo in Fall
The nearest coast averages about 29°C across fall — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 30 km away) is warmest in September at about 29°C and coldest in February near 26°C.
The water stays above 20°C all year — warm enough for a swim any month.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 27 | 26 | 26 | 27 | 27 | 28 | 28 | 29 | 29 | 29 | 28 | 27 |
| Comfort | Warm | Warm | Warm | Warm | Warm | Warm | Tropical | Tropical | Tropical | Tropical | Tropical | Warm |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 27 | Warm |
| Feb | 26 | Warm |
| Mar | 26 | Warm |
| Apr | 27 | Warm |
| May | 27 | Warm |
| Jun | 28 | Warm |
| Jul | 28 | Tropical |
| Aug | 29 | Tropical |
| Sep | 29 | Tropical |
| Oct | 29 | Tropical |
| Nov | 28 | Tropical |
| Dec | 27 | Warm |
UV index in Guaynabo in Fall
Clear-sky midday UV across fall averages around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Guaynabo peaks around April 13 at about 13 (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 | 13 | 11 | 12 | 12 | 12 | 12 | 10 | 8 | 7 |
| Level | Very high | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Very high | Very high | High |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 8 | Very high |
| Feb | 10 | Extreme |
| Mar | 12 | Extreme |
| Apr | 13 | Extreme |
| May | 11 | Extreme |
| Jun | 12 | Extreme |
| Jul | 12 | Extreme |
| Aug | 12 | Extreme |
| Sep | 12 | Extreme |
| Oct | 10 | Very high |
| Nov | 8 | Very high |
| Dec | 7 | High |
Air quality in Guaynabo in Fall
Average fine-particle pollution (PM2.5) through the year — so you can see where fall falls, not just the annual average.
Air quality in Guaynabo is worst in July — around 25 µg/m³ PM2.5 (moderate), about 4.7× the cleanest month (January, 5 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) | 5 | 7 | 7 | 9 | 14 | 24 | 25 | 20 | 15 | 15 | 8 | 5 |
| Level | Good | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 5 | Good |
| Feb | 7 | Good |
| Mar | 7 | Good |
| Apr | 9 | Good |
| May | 14 | Moderate |
| Jun | 24 | Moderate |
| Jul | 25 | Moderate |
| Aug | 20 | Moderate |
| Sep | 15 | Moderate |
| Oct | 15 | Moderate |
| Nov | 8 | Good |
| Dec | 5 | Good |
Where is Guaynabo?
Guaynabo sits at 18.4°N, 66.1°W, 47 m above sea level, in Puerto Rico. The nearest listed city is Bayamón, 7.0 km away.
Topography around Guaynabo
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Guaynabo.
Within 3 km, the terrain around Guaynabo has only modest variations in elevation — a maximum elevation change of 192 m around an average of 64 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 654 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,308 m.
The land around Guaynabo is covered by trees (51%) and artificial surfaces (45%) within 3 km, trees (54%) and artificial surfaces (28%) within 16 km, and water (61%) and trees (30%) within 80 km.
Puerto Rico travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 78% of US
- price level, 2025
- GDP per capita
- $40,620
- 2025
- Happiness
- 7.0 / 10
- World Happiness, 2015
- Safe drinking water
- 99%
- of population, 2024
- Homicide rate
- 14.6
- per 100k, 2023
- 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 Guaynabo (18.3575°, -66.111°, elevation 47 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.