Tumon weather in September

In September, Tumon sees average daytime highs of 28°C and overnight lows near 26°C, with 314 mm of rain across 27.2 wet days and about 12.1 hours of daylight. It is the 2nd-warmest and 2nd-wettest month of the year here.

Day-to-day highs hold fairly steady near 28°C through the month. The sky is clear or mostly clear about 6% of the time in September, and the air most often feels miserable.

Daylight stretches from about 12 h 18 min at the start of September to 11 h 54 min by month's end. Set against the rest of the year, September is Tumon's 11th-clearest and 12th-windiest month. For the whole year in context, see Tumon's year-round climate.

Daytime high: 28°; 2nd warmest
Overnight low: 26°; 6th coldest
Rainfall: 314 mm; 27.2 wet days
Daylight: 12 h 06 min; 6:13 AM – 6:17 PM
Cloud cover: 85%; 11th clearest
Wind: 18 km/h; 12th windiest
Solar energy: 5.15 kWh/m²
Travel score: 3.3; out of 10

Tumon is village of Guam, a municipality in the United States territory.

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

← August Tumon year-round climate October →Best places to visit in September

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Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 28°C through the month.

A typical September day in Tumon reaches about 28°C in the afternoon and slips back to 26°C overnight — a 2°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 29°C. Set against its neighbours, September runs on par with August and on par with October.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Avg high (°C)	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28	28
Avg low (°C)	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26	26

	Avg high (°C)	Avg low (°C)
1	28	26
2	28	26
3	28	26
4	28	26
5	28	26
6	28	26
7	28	26
8	28	26
9	28	26
10	28	26
11	28	26
12	28	26
13	28	26
14	28	26
15	28	26
16	28	26
17	28	26
18	28	26
19	28	26
20	28	26
21	28	26
22	28	26
23	28	26
24	28	26
25	28	26
26	28	26
27	28	26
28	28	26
29	28	26
30	28	26

How September really feels in Tumon

Once humidity and wind are folded in, September averages 30 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C

heat index over the day's high

Days feeling ≤ 0°C

wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Tumon weather by month

How September compares with the rest of the year at a glance. September is the 2nd-warmest and 2nd-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Daylight (hours)	Travel score
Jan	27° / 26°	71	14.7	11.3	6.0
Feb	27° / 26°	51	11.3	11.6	6.3
Mar	27° / 26°	45	10.2	11.9	6.7
Apr	27° / 26°	67	11.1	12.3	6.5
May	28° / 27°	81	15	12.6	5.6
Jun	28° / 27°	140	20.4	12.8	4.4
Jul	28° / 26°	273	28.4	12.7	3.3
Aug	28° / 26°	350	29.2	12.4	3.2
Sep	28° / 26°	314	27.2	12.1	3.3
Oct	28° / 26°	279	27.5	11.7	3.6
Nov	28° / 27°	175	21.5	11.4	4.5
Dec	28° / 26°	93	16.8	11.2	5.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 6% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 8% of September, with mostly cloudy or overcast conditions the remaining 86%.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Clearer (%)	15	15	15	15	14	13	12	12	11	10	10	10	10	10	10	10	12	13	13	13	14	15	15	16	17	17	18	19	19	19
Cloudier (%)	85	85	85	85	86	87	88	88	89	90	90	90	90	90	90	90	88	87	87	87	86	85	85	84	83	83	82	81	81	81

	Clearer (%)	Cloudier (%)
1	15	85
2	15	85
3	15	85
4	15	85
5	14	86
6	13	87
7	12	88
8	12	88
9	11	89
10	10	90
11	10	90
12	10	90
13	10	90
14	10	90
15	10	90
16	10	90
17	12	88
18	13	87
19	13	87
20	13	87
21	14	86
22	15	85
23	15	85
24	16	84
25	17	83
26	17	83
27	18	82
28	19	81
29	19	81
30	19	81

Chance of precipitation in September

Any precipitation

Tumon gets around 314 mm of rain over 27.2 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 91% and peaks near 92% on the wettest days.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Rain chance (%)	91	91	91	91	91	91	91	91	91	91	91	92	91	91	91	91	91	91	90	90	90	90	90	90	90	90	90	90	90	91

	Rain chance (%)
1	91
2	91
3	91
4	91
5	91
6	91
7	91
8	91
9	91
10	91
11	91
12	92
13	91
14	91
15	91
16	91
17	91
18	91
19	90
20	90
21	90
22	90
23	90
24	90
25	90
26	90
27	90
28	90
29	90
30	91

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels miserable — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the miserable band about 75% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Oppressive (%)	20	20	21	21	21	22	23	23	24	25	25	26	26	27	27	27	27	27	27	27	26	26	26	26	25	25	25	25	25	25
Miserable (%)	80	80	79	79	79	78	77	77	76	75	75	74	74	73	73	73	73	73	73	73	74	74	74	74	75	75	75	75	75	75

	Oppressive (%)	Miserable (%)
1	20	80
2	20	80
3	21	79
4	21	79
5	21	79
6	22	78
7	23	77
8	23	77
9	24	76
10	25	75
11	25	75
12	26	74
13	26	74
14	27	73
15	27	73
16	27	73
17	27	73
18	27	73
19	27	73
20	27	73
21	26	74
22	26	74
23	26	74
24	26	74
25	25	75
26	25	75
27	25	75
28	25	75
29	25	75
30	25	75

Wind in September

Winds average 18 km/h in September, the calmest month.

Across September, daily wind ranges from about 17 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Wind speed (km/h)	17	17	17	17	17	17	17	17	18	18	18	18	18	18	18	18	18	18	18	18	18	18	18	18	18	18	18	18	18	18
Feels	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze

	Wind speed (km/h)	Feels
1	17	light breeze
2	17	light breeze
3	17	light breeze
4	17	light breeze
5	17	light breeze
6	17	light breeze
7	17	light breeze
8	17	light breeze
9	18	light breeze
10	18	light breeze
11	18	light breeze
12	18	light breeze
13	18	light breeze
14	18	light breeze
15	18	light breeze
16	18	light breeze
17	18	light breeze
18	18	light breeze
19	18	light breeze
20	18	light breeze
21	18	light breeze
22	18	light breeze
23	18	light breeze
24	18	light breeze
25	18	light breeze
26	18	light breeze
27	18	light breeze
28	18	light breeze
29	18	light breeze
30	18	light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 18 min at the start of September to 11 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 24 minutes over September. Sunrise moves from 6:13 AM to 6:13 AM, and sunset from 6:29 PM to 6:07 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Daylight (h)	12.3	12.3	12.2	12.2	12.2	12.2	12.2	12.2	12.2	12.2	12.1	12.1	12.1	12.1	12.1	12.1	12.1	12.0	12.0	12.0	12.0	12.0	12.0	12.0	12.0	11.9	11.9	11.9	11.9	11.9
Sunrise (AM)	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13	6:13
Sunset (PM)	6:29	6:28	6:27	6:26	6:26	6:25	6:24	6:23	6:23	6:22	6:21	6:20	6:20	6:19	6:18	6:17	6:17	6:16	6:15	6:14	6:14	6:13	6:12	6:11	6:11	6:10	6:09	6:08	6:08	6:07

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	12.3	6:13	6:29
2	12.3	6:13	6:28
3	12.2	6:13	6:27
4	12.2	6:13	6:26
5	12.2	6:13	6:26
6	12.2	6:13	6:25
7	12.2	6:13	6:24
8	12.2	6:13	6:23
9	12.2	6:13	6:23
10	12.2	6:13	6:22
11	12.1	6:13	6:21
12	12.1	6:13	6:20
13	12.1	6:13	6:20
14	12.1	6:13	6:19
15	12.1	6:13	6:18
16	12.1	6:13	6:17
17	12.1	6:13	6:17
18	12.0	6:13	6:16
19	12.0	6:13	6:15
20	12.0	6:13	6:14
21	12.0	6:13	6:14
22	12.0	6:13	6:13
23	12.0	6:13	6:12
24	12.0	6:13	6:11
25	12.0	6:13	6:11
26	11.9	6:13	6:10
27	11.9	6:13	6:09
28	11.9	6:13	6:08
29	11.9	6:13	6:08
30	11.9	6:13	6:07

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.15 kWh/m².

For context, solar energy here swings from a low near 4.86 kWh/m² to a high of 6.68 kWh/m² in April across the year — September's 5.15 kWh/m² falls in the middle.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Solar energy (kWh/m²)	5.3	5.3	5.3	5.3	5.3	5.3	5.3	5.3	5.2	5.2	5.2	5.2	5.2	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1
Level	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright

	Solar energy (kWh/m²)	Level
1	5.3	Bright
2	5.3	Bright
3	5.3	Bright
4	5.3	Bright
5	5.3	Bright
6	5.3	Bright
7	5.3	Bright
8	5.3	Bright
9	5.2	Bright
10	5.2	Bright
11	5.2	Bright
12	5.2	Bright
13	5.2	Bright
14	5.1	Bright
15	5.1	Bright
16	5.1	Bright
17	5.1	Bright
18	5.1	Bright
19	5.1	Bright
20	5.1	Bright
21	5.1	Bright
22	5.1	Bright
23	5.1	Bright
24	5.1	Bright
25	5.1	Bright
26	5.1	Bright
27	5.1	Bright
28	5.1	Bright
29	5.1	Bright
30	5.1	Bright

Planning a trip in September

Hazard calendar for Tumon

In seasonPeak

In September, Tumon sits inside its pacific typhoon and monsoon season. The full year is below, with each hazard's peak months called out.

Tumon sits in the Pacific typhoon belt; the season peaks July–October.

Tumon's monsoon runs July–November, when most of the year's rain falls.

Pacific typhoon

Monsoon

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Is September a good time to visit Tumon?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

3.3

Sightseeing

10th-best month of the year

3.9

Beach & pool

11th-best month of the year

September is a weaker month for outdoor sightseeing in Tumon.

What to pack for Tumon in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Tumon sees daytime highs around 28°C and nights near 26°C. Pack light clothes and rain gear. Worth having: sun protection. About 27 days see rain.

light clothesrain gearsun protection

Sea temperature near Tumon in September

The nearest coast averages about 29°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 16 km away) is warmest in July at about 29°C and coldest in February near 28°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)	28	28	28	28	29	29	29	29	29	29	29	28
Comfort	Warm	Warm	Warm	Tropical	Tropical	Tropical	Tropical	Tropical	Tropical	Tropical	Tropical	Tropical

	Sea temperature (°C)	Comfort
Jan	28	Warm
Feb	28	Warm
Mar	28	Warm
Apr	28	Tropical
May	29	Tropical
Jun	29	Tropical
Jul	29	Tropical
Aug	29	Tropical
Sep	29	Tropical
Oct	29	Tropical
Nov	29	Tropical
Dec	28	Tropical

UV index in Tumon in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 13 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Tumon peaks around August 18 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 9 (very 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)	10	11	13	13	13	12	13	14	13	12	10	9
Level	Very high	Extreme	Extreme	Extreme	Extreme	Extreme	Extreme	Extreme	Extreme	Extreme	Extreme	Very high

	UV index (midday)	Level
Jan	10	Very high
Feb	11	Extreme
Mar	13	Extreme
Apr	13	Extreme
May	13	Extreme
Jun	12	Extreme
Jul	13	Extreme
Aug	14	Extreme
Sep	13	Extreme
Oct	12	Extreme
Nov	10	Extreme
Dec	9	Very high

Location & terrain

Where is Tumon?

Tumon sits at 13.5°N, 144.8°E, 13 m above sea level, in Guam. The nearest listed city is Tamuning-Tumon-Harmon Village, 0.0 km away.

Topography around Tumon

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Tumon.

Within 3 km, the terrain around Tumon has only modest variations in elevation — a maximum elevation change of 109 m around an average of 32 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 308 m; within 80 km, significant variations in elevation — a maximum elevation change of 387 m.

The land around Tumon is covered by water (31%), trees (25%) and artificial surfaces (23%) within 3 km, water (59%) and trees (28%) within 16 km, and water (94%) within 80 km.

3 km

109 m

water 31%

16 km

308 m

water 59%

80 km

387 m

water 94%

treesgrasslandartificial surfacesbare terrainwater

← August Tumon year-round climate October →Best places to visit in September

September weather nearby: Tamuning-Tumon-Harmon Village 0.0 km · Hagatna 4.0 km · Mangilao Village 5.0 km · Dededo Village 7.0 km · Yigo Village 13 km · Saipan 219 km · Ngerulmud 1,294 km · Koror 1,318 km

Guam travel facts

Power plugs: Type A / B; 110 V · 60 Hz
GDP per capita: $41,833; 2022
Safe drinking water: 94%; of population, 2024
Homicide rate: 4.3; per 100k, 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 Tumon (13.4875°, 144.7814°, elevation 13 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. 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).

	Avg high (°C)	Avg low (°C)
1	28	26
2	28	26
3	28	26
4	28	26
5	28	26
6	28	26
7	28	26
8	28	26
9	28	26
10	28	26
11	28	26
12	28	26
13	28	26
14	28	26
15	28	26
16	28	26
17	28	26
18	28	26
19	28	26
20	28	26
21	28	26
22	28	26
23	28	26
24	28	26
25	28	26
26	28	26
27	28	26
28	28	26
29	28	26
30	28	26

	Clearer (%)	Cloudier (%)
1	15	85
2	15	85
3	15	85
4	15	85
5	14	86
6	13	87
7	12	88
8	12	88
9	11	89
10	10	90
11	10	90
12	10	90
13	10	90
14	10	90
15	10	90
16	10	90
17	12	88
18	13	87
19	13	87
20	13	87
21	14	86
22	15	85
23	15	85
24	16	84
25	17	83
26	17	83
27	18	82
28	19	81
29	19	81
30	19	81

	Rain chance (%)
1	91
2	91
3	91
4	91
5	91
6	91
7	91
8	91
9	91
10	91
11	91
12	92
13	91
14	91
15	91
16	91
17	91
18	91
19	90
20	90
21	90
22	90
23	90
24	90
25	90
26	90
27	90
28	90
29	90
30	91

	Oppressive (%)	Miserable (%)
1	20	80
2	20	80
3	21	79
4	21	79
5	21	79
6	22	78
7	23	77
8	23	77
9	24	76
10	25	75
11	25	75
12	26	74
13	26	74
14	27	73
15	27	73
16	27	73
17	27	73
18	27	73
19	27	73
20	27	73
21	26	74
22	26	74
23	26	74
24	26	74
25	25	75
26	25	75
27	25	75
28	25	75
29	25	75
30	25	75

	Avg high (°C)	Avg low (°C)
1	28	26
2	28	26
3	28	26
4	28	26
5	28	26
6	28	26
7	28	26
8	28	26
9	28	26
10	28	26
11	28	26
12	28	26
13	28	26
14	28	26
15	28	26
16	28	26
17	28	26
18	28	26
19	28	26
20	28	26
21	28	26
22	28	26
23	28	26
24	28	26
25	28	26
26	28	26
27	28	26
28	28	26
29	28	26
30	28	26

	Clearer (%)	Cloudier (%)
1	15	85
2	15	85
3	15	85
4	15	85
5	14	86
6	13	87
7	12	88
8	12	88
9	11	89
10	10	90
11	10	90
12	10	90
13	10	90
14	10	90
15	10	90
16	10	90
17	12	88
18	13	87
19	13	87
20	13	87
21	14	86
22	15	85
23	15	85
24	16	84
25	17	83
26	17	83
27	18	82
28	19	81
29	19	81
30	19	81

	Rain chance (%)
1	91
2	91
3	91
4	91
5	91
6	91
7	91
8	91
9	91
10	91
11	91
12	92
13	91
14	91
15	91
16	91
17	91
18	91
19	90
20	90
21	90
22	90
23	90
24	90
25	90
26	90
27	90
28	90
29	90
30	91

	Oppressive (%)	Miserable (%)
1	20	80
2	20	80
3	21	79
4	21	79
5	21	79
6	22	78
7	23	77
8	23	77
9	24	76
10	25	75
11	25	75
12	26	74
13	26	74
14	27	73
15	27	73
16	27	73
17	27	73
18	27	73
19	27	73
20	27	73
21	26	74
22	26	74
23	26	74
24	26	74
25	25	75
26	25	75
27	25	75
28	25	75
29	25	75
30	25	75

	Avg high (°C)	Avg low (°C)
1	28	26
2	28	26
3	28	26
4	28	26
5	28	26
6	28	26
7	28	26
8	28	26
9	28	26
10	28	26
11	28	26
12	28	26
13	28	26
14	28	26
15	28	26
16	28	26
17	28	26
18	28	26
19	28	26
20	28	26
21	28	26
22	28	26
23	28	26
24	28	26
25	28	26
26	28	26
27	28	26
28	28	26
29	28	26
30	28	26

	Clearer (%)	Cloudier (%)
1	15	85
2	15	85
3	15	85
4	15	85
5	14	86
6	13	87
7	12	88
8	12	88
9	11	89
10	10	90
11	10	90
12	10	90
13	10	90
14	10	90
15	10	90
16	10	90
17	12	88
18	13	87
19	13	87
20	13	87
21	14	86
22	15	85
23	15	85
24	16	84
25	17	83
26	17	83
27	18	82
28	19	81
29	19	81
30	19	81

	Rain chance (%)
1	91
2	91
3	91
4	91
5	91
6	91
7	91
8	91
9	91
10	91
11	91
12	92
13	91
14	91
15	91
16	91
17	91
18	91
19	90
20	90
21	90
22	90
23	90
24	90
25	90
26	90
27	90
28	90
29	90
30	91

	Oppressive (%)	Miserable (%)
1	20	80
2	20	80
3	21	79
4	21	79
5	21	79
6	22	78
7	23	77
8	23	77
9	24	76
10	25	75
11	25	75
12	26	74
13	26	74
14	27	73
15	27	73
16	27	73
17	27	73
18	27	73
19	27	73
20	27	73
21	26	74
22	26	74
23	26	74
24	26	74
25	25	75
26	25	75
27	25	75
28	25	75
29	25	75
30	25	75