Guam climate guide

Temperature in Guam (°C)

  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Max temperature (daytime)
30°C maximum daytime temperature in January in Guam (Agana)30
30°C maximum daytime temperature in February in Guam (Agana)30
30°C maximum daytime temperature in March in Guam (Agana)30
31°C maximum daytime temperature in April in Guam (Agana)31
31°C maximum daytime temperature in May in Guam (Agana)31
31°C maximum daytime temperature in June in Guam (Agana)31
31°C maximum daytime temperature in July in Guam (Agana)31
31°C maximum daytime temperature in August in Guam (Agana)31
31°C maximum daytime temperature in September in Guam (Agana)31
31°C maximum daytime temperature in October in Guam (Agana)31
31°C maximum daytime temperature in November in Guam (Agana)31
30°C maximum daytime temperature in December in Guam (Agana)30
Min temperature (night-time)
24°C minimum night-time temperature in January in Guam (Agana)24
24°C minimum night-time temperature in February in Guam (Agana)24
24°C minimum night-time temperature in March in Guam (Agana)24
24°C minimum night-time temperature in April in Guam (Agana)24
25°C minimum night-time temperature in May in Guam (Agana)25
25°C minimum night-time temperature in June in Guam (Agana)25
25°C minimum night-time temperature in July in Guam (Agana)25
25°C minimum night-time temperature in August in Guam (Agana)25
25°C minimum night-time temperature in September in Guam (Agana)25
25°C minimum night-time temperature in October in Guam (Agana)25
25°C minimum night-time temperature in November in Guam (Agana)25
24°C minimum night-time temperature in December in Guam (Agana)24
Sea temperature
28°C sea temperature in January in Guam (Agana)28
27°C sea temperature in February in Guam (Agana)27
27°C sea temperature in March in Guam (Agana)27
28°C sea temperature in April in Guam (Agana)28
28°C sea temperature in May in Guam (Agana)28
29°C sea temperature in June in Guam (Agana)29
29°C sea temperature in July in Guam (Agana)29
29°C sea temperature in August in Guam (Agana)29
29°C sea temperature in September in Guam (Agana)29
29°C sea temperature in October in Guam (Agana)29
29°C sea temperature in November in Guam (Agana)29
28°C sea temperature in December in Guam (Agana)28

Sunshine & Daylight in Guam

  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Daily hours of sunshine
Daily hours of daylight
11 hours of daylight per day in January in Guam (Agana)11
12 hours of daylight per day in February in Guam (Agana)12
12 hours of daylight per day in March in Guam (Agana)12
12 hours of daylight per day in April in Guam (Agana)12
13 hours of daylight per day in May in Guam (Agana)13
13 hours of daylight per day in June in Guam (Agana)13
13 hours of daylight per day in July in Guam (Agana)13
13 hours of daylight per day in August in Guam (Agana)13
12 hours of daylight per day in September in Guam (Agana)12
12 hours of daylight per day in October in Guam (Agana)12
12 hours of daylight per day in November in Guam (Agana)12
11 hours of daylight per day in December in Guam (Agana)11

Rainfall in Guam

  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Number of days with some rain
23 days with some rainfall in January in Guam (Agana)23
19 days with some rainfall in February in Guam (Agana)19
20 days with some rainfall in March in Guam (Agana)20
19 days with some rainfall in April in Guam (Agana)19
20 days with some rainfall in May in Guam (Agana)20
17 days with some rainfall in June in Guam (Agana)17
19 days with some rainfall in July in Guam (Agana)19
20 days with some rainfall in August in Guam (Agana)20
19 days with some rainfall in September in Guam (Agana)19
22 days with some rainfall in October in Guam (Agana)22
22 days with some rainfall in November in Guam (Agana)22
23 days with some rainfall in December in Guam (Agana)23
Average monthly rainfall (mm)
130 mm monthly rainfall in January in Guam (Agana)130
111 mm monthly rainfall in February in Guam (Agana)111
89 mm monthly rainfall in March in Guam (Agana)89
102 mm monthly rainfall in April in Guam (Agana)102
142 mm monthly rainfall in May in Guam (Agana)142
162 mm monthly rainfall in June in Guam (Agana)162
273 mm monthly rainfall in July in Guam (Agana)273
363 mm monthly rainfall in August in Guam (Agana)363
343 mm monthly rainfall in September in Guam (Agana)343
317 mm monthly rainfall in October in Guam (Agana)317
228 mm monthly rainfall in November in Guam (Agana)228
150 mm monthly rainfall in December in Guam (Agana)150

More climate for Guam

  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
UV Index (Maximum)
UV (maximum) index 10 (Very High) in January in Guam (Agana)10
UV (maximum) index 11+ (Extreme) in February in Guam (Agana)11
UV (maximum) index 11+ (Extreme) in March in Guam (Agana)11
UV (maximum) index 11+ (Extreme) in April in Guam (Agana)11
UV (maximum) index 11+ (Extreme) in May in Guam (Agana)11
UV (maximum) index 11+ (Extreme) in June in Guam (Agana)11
UV (maximum) index 11+ (Extreme) in July in Guam (Agana)11
UV (maximum) index 11+ (Extreme) in August in Guam (Agana)11
UV (maximum) index 11+ (Extreme) in September in Guam (Agana)11
UV (maximum) index 11+ (Extreme) in October in Guam (Agana)11
UV (maximum) index 10 (Very High) in November in Guam (Agana)10
UV (maximum) index 9 (Very High) in December in Guam (Agana)9
Heat & Humidity
High heat & humidity in January in Guam (Agana)H
High heat & humidity in February in Guam (Agana)H
High heat & humidity in March in Guam (Agana)H
High heat & humidity in April in Guam (Agana)H
Very high heat & humidity in May in Guam (Agana)VH
Very high heat & humidity in June in Guam (Agana)VH
Very high heat & humidity in July in Guam (Agana)VH
Very high heat & humidity in August in Guam (Agana)VH
Very high heat & humidity in September in Guam (Agana)VH
Very high heat & humidity in October in Guam (Agana)VH
Very high heat & humidity in November in Guam (Agana)VH
High heat & humidity in December in Guam (Agana)H

Note: 0 = None, L = Low, M = Moderate, H = High, VH = Very high, E = Extreme

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

The climate guide for Guam shows long term monthly weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

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Metric (°C / mm)  |  Imperial (°F / inches)

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Guam climate overview

Guam is the most southerly island of the Marianas Archipelago, in the Pacific Ocean over 2,000 kilometres (1,250 miles) to the east of the Philippines. Colonial Spanish influences are still evident in the lively capital Agana, although Spain ceded Guam to the United States in 1898, and the American government now maintains two large bases on the island.

Tourism is Guam's leading industry, with visitors arriving mainly from Japan in search of duty free shopping. Though the island has some nice beaches the best is off-limits to non-military personnel.

The northern two-thirds of Guam consists of a raised rolling limestone plateau with pockets of dense jungle that give the island a truly tropical feel. The northern coast is rugged with cliffs dropping precipitously into the sea, where huge Pacific swells have hollowed out an intricate tunnel of sea-caves along the base.

The south of the island is basically volcanic with an elongated mountain ridge dividing the inland valleys and coastline. The far south widens into a landscape of high hills and valleys cut by streams and waterfalls. The rolling hills, which are steep in places are mostly grass-covered, with trees growing only in the protected more fertile valleys. The best beaches are found along the sheltered coastline of the west, home to blindingly white sand and coral reefs.

The climate is tropical with rainfall in all months becoming heavy during the peak rainy season from July to December. Rainfall eases during the drier season from January to June when March is usually the sunniest month. Temperatures are consistently warm or hot all year with high heat and humidity.

On the average, one typhoon passes close by Guam each year usually between the months of August and December.

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