★ January30° · ☂ 18 ★ February30° · ☂ 13 March 31° · ☂ 15 April 31° · ☂ 16 May 32° · ☂ 17 June 31° · ☂ 19 July 31° · ☂ 22 August 31° · ☂ 23 September 31° · ☂ 24 October 31° · ☂ 24 November 31° · ☂ 20 ★ December30° · ☂ 19 Guam in September:hot, rain almost daily Guam · Records from 2006 to 2025. Not a forecast.
Mean high 31° Hottest day 32.1° (2017)
Mean low 25° Coldest night 23.1° (2019)
Rain days 24 days 16-29 by year
Rainfall 444mm Daylight 12.4 → 12.0 h
Guam's 12 months i Best: December to February
1 2 3 4 5 6 7 8 9 10 11 12
Trip types Beach Poorfrequent rain and storm risk Sightseeing on foot Poorhot, frequent rain, muggy and storm risk
Humidity 84% 30 muggy days
Clear days 0 days 24 overcast days
Mean wind 17 km/h 2 windy days
Sea temperature 29.9° 29.6-30.2° by year (last 6)
Sunrise / sunset (15th) 06:10 / 18:22 Daylight 12.4 → 12.0 h
Guam in September One of the months with the most rainy days, right in the middle of typhoon season. Check the weather news often before and during the trip. Choose flights and hotels with flexible change rules so a typhoon costs you less.
September brought serious heat to Guam, 31°C on a typical afternoon and 25°C overnight. Early mornings were the best time to be outside. Rain was a regular part of the month, showing up on 24 days on average. Year to year it swung widely, from 16 rain days in 2006 to 29 in 2009.
Highs topped 30°C on 28 days of the month on average. Mixing in indoor stops at midday made sense. Rain days averaged 19 mm each, so when it rained it rained properly.
Typhoons i 4 of the last 20 years had a tropical storm pass within 300 km this month.
Bebinca (2024), 59 km away tropical storm Mangkhut (2018), 85 km away typhoon strength Kong-Rey (2018), 166 km away tropical storm 1 1 2 1 3 2 4 3 5 1 6 3 7 4 8 4 9 6 10 4 11 1 12
Date by date i Sun
Mon
Tue
Wed
Thu
Fri
Sat
Week
September 1 Wednesday 1 rain in 13 of 20 yrs 13/20 31° 25° September 2 Thursday 2 rain in 18 of 20 yrs 18/20 31° 24° September 3 Friday 3 rain in 17 of 20 yrs 17/20 31° 24° September 4 Saturday 4 rain in 11 of 20 yrs 11/20 31° 25° 1-4 rain on 74% of days 31° 24°
September 5 Sunday 5 rain in 12 of 20 yrs 12/20 31° 25° September 6 Monday 6 rain in 16 of 20 yrs 16/20 31° 25° September 7 Tuesday 7 rain in 16 of 20 yrs 16/20 31° 24° September 8 Wednesday 8 rain in 15 of 20 yrs 15/20 31° 24° September 9 Thursday 9 rain in 15 of 20 yrs 15/20 31° 24° September 10 Friday 10 rain in 15 of 20 yrs 15/20 31° 25° September 11 Saturday 11 rain in 17 of 20 yrs 17/20 31° 24° 5-11 rain on 76% of days 31° 24°
September 12 Sunday 12 rain in 16 of 20 yrs 16/20 31° 24° September 13 Monday 13 rain in 16 of 20 yrs 16/20 31° 25° September 14 Tuesday 14 rain in 14 of 20 yrs 14/20 31° 25° September 15 Wednesday 15 rain in 18 of 20 yrs 18/20 31° 24° September 16 Thursday 16 rain in 17 of 20 yrs 17/20 31° 24° September 17 Friday 17 rain in 18 of 20 yrs 18/20 31° 24° September 18 Saturday 18 rain in 18 of 20 yrs 18/20 31° 24° 12-18 rain on 84% of days 31° 24°
September 19 Sunday 19 rain in 16 of 20 yrs 16/20 31° 24° September 20 Monday 20 rain in 16 of 20 yrs 16/20 31° 24° September 21 Tuesday 21 rain in 17 of 20 yrs 17/20 31° 25° September 22 Wednesday 22 rain in 16 of 20 yrs 16/20 31° 24° September 23 Thursday 23 rain in 16 of 20 yrs 16/20 31° 24° September 24 Friday 24 rain in 15 of 20 yrs 15/20 31° 25° September 25 Saturday 25 rain in 15 of 20 yrs 15/20 31° 24° 19-25 rain on 79% of days 31° 24°
September 26 Sunday 26 rain in 17 of 20 yrs 17/20 31° 24° September 27 Monday 27 rain in 17 of 20 yrs 17/20 31° 24° September 28 Tuesday 28 rain in 15 of 20 yrs 15/20 31° 24° September 29 Wednesday 29 rain in 15 of 20 yrs 15/20 31° 24° September 30 Thursday 30 rain in 15 of 20 yrs 15/20 31° 24°
26-30 rain on 79% of days 31° 24°
Rain was common on almost every date this month, so the shades compare dates within this month.
1-4 rain on 74% of days 31° 24° 5-11 rain on 76% of days 31° 24° 12-18 rain on 84% of days 31° 24° 19-25 rain on 79% of days 31° 24° 26-30 rain on 79% of days 31° 24°
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Week
September 1 Friday 1 rain in 13 of 20 yrs 13/20 31° 25° September 2 Saturday 2 rain in 18 of 20 yrs 18/20 31° 24° 1-2 rain on 78% of days 31° 24°
September 3 Sunday 3 rain in 17 of 20 yrs 17/20 31° 24° September 4 Monday 4 rain in 11 of 20 yrs 11/20 31° 25° September 5 Tuesday 5 rain in 12 of 20 yrs 12/20 31° 25° September 6 Wednesday 6 rain in 16 of 20 yrs 16/20 31° 25° September 7 Thursday 7 rain in 16 of 20 yrs 16/20 31° 24° September 8 Friday 8 rain in 15 of 20 yrs 15/20 31° 24° September 9 Saturday 9 rain in 15 of 20 yrs 15/20 31° 24° 3-9 rain on 73% of days 31° 24°
September 10 Sunday 10 rain in 15 of 20 yrs 15/20 31° 25° September 11 Monday 11 rain in 17 of 20 yrs 17/20 31° 24° September 12 Tuesday 12 rain in 16 of 20 yrs 16/20 31° 24° September 13 Wednesday 13 rain in 16 of 20 yrs 16/20 31° 25° September 14 Thursday 14 rain in 14 of 20 yrs 14/20 31° 25° September 15 Friday 15 rain in 18 of 20 yrs 18/20 31° 24° September 16 Saturday 16 rain in 17 of 20 yrs 17/20 31° 24° 10-16 rain on 81% of days 31° 25°
September 17 Sunday 17 rain in 18 of 20 yrs 18/20 31° 24° September 18 Monday 18 rain in 18 of 20 yrs 18/20 31° 24° September 19 Tuesday 19 rain in 16 of 20 yrs 16/20 31° 24° September 20 Wednesday 20 rain in 16 of 20 yrs 16/20 31° 24° September 21 Thursday 21 rain in 17 of 20 yrs 17/20 31° 25° September 22 Friday 22 rain in 16 of 20 yrs 16/20 31° 24° September 23 Saturday 23 rain in 16 of 20 yrs 16/20 31° 24° 17-23 rain on 84% of days 31° 24°
September 24 Sunday 24 rain in 15 of 20 yrs 15/20 31° 25° September 25 Monday 25 rain in 15 of 20 yrs 15/20 31° 24° September 26 Tuesday 26 rain in 17 of 20 yrs 17/20 31° 24° September 27 Wednesday 27 rain in 17 of 20 yrs 17/20 31° 24° September 28 Thursday 28 rain in 15 of 20 yrs 15/20 31° 24° September 29 Friday 29 rain in 15 of 20 yrs 15/20 31° 24° September 30 Saturday 30 rain in 15 of 20 yrs 15/20 31° 24° 24-30 rain on 78% of days 31° 24°
Rain was common on almost every date this month, so the shades compare dates within this month.
1-2 rain on 78% of days 31° 24° 3-9 rain on 73% of days 31° 24° 10-16 rain on 81% of days 31° 25° 17-23 rain on 84% of days 31° 24° 24-30 rain on 78% of days 31° 24°
Tap another date to change
2006 none
2007 15mm
2008 19mm
2009 23mm
2010 8mm
2011 55mm
2012 3mm
2013 none
2014 2mm
2015 2mm
2016 3mm
2017 9mm
2018 13mm
2019 14mm
2020 1mm
2021 10mm
2022 4mm
2023 3mm
2024 6mm
2025 17mm
Holidays in September (2027) 1 Local public holiday or break (busier, pricier)
Your trip dates, the past 20 years Trip dates September 1 (Wed) 2 (Thu) 3 (Fri) 4 (Sat) 5 (Sun) 6 (Mon) 7 (Tue) 8 (Wed) 9 (Thu) 10 (Fri) 11 (Sat) 12 (Sun) 13 (Mon) 14 (Tue) 15 (Wed) 16 (Thu) 17 (Fri) 18 (Sat) 19 (Sun) 20 (Mon) 21 (Tue) 22 (Wed) 23 (Thu) 24 (Fri) 25 (Sat) 26 (Sun) 27 (Mon) 28 (Tue) 29 (Wed) 30 (Thu) ~ September 1 (Wed) 2 (Thu) 3 (Fri) 4 (Sat) 5 (Sun) 6 (Mon) 7 (Tue) 8 (Wed) 9 (Thu) 10 (Fri) 11 (Sat) 12 (Sun) 13 (Mon) 14 (Tue) 15 (Wed) 16 (Thu) 17 (Fri) 18 (Sat) 19 (Sun) 20 (Mon) 21 (Tue) 22 (Wed) 23 (Thu) 24 (Fri) 25 (Sat) 26 (Sun) 27 (Mon) 28 (Tue) 29 (Wed) 30 (Thu) 1-7 8-14 15-21 22-end Whole month
You can also click two dates on the axis. Hover a cell to see that day's rain. By year Driest trips first
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
Trip rain days Month rain days Tap a date to start, tap another to end. Each cell is that date in one year. '06 '07 '08 '09 '10 '11 '12 '13 '14 '15 '16 '17 '18 '19 '20 '21 '22 '23 '24 '25
of 20 1 Wed Pick September 1
13 2 Thu Pick September 2
18 3 Fri Pick September 3
17 4 Sat Pick September 4
11 5 Sun Pick September 5
12 6 Mon Pick September 6
16 7 Tue Pick September 7
16 8 Wed Pick September 8
15 9 Thu Pick September 9
15 10 Fri Pick September 10
15 11 Sat Pick September 11
17 12 Sun Pick September 12
16 13 Mon Pick September 13
16 14 Tue Pick September 14
14 15 Wed Pick September 15
18 16 Thu Pick September 16
17 17 Fri Pick September 17
18 18 Sat Pick September 18
18 19 Sun Pick September 19
16 20 Mon Pick September 20
16 21 Tue Pick September 21
17 22 Wed Pick September 22
16 23 Thu Pick September 23
16 24 Fri Pick September 24
15 25 Sat Pick September 25
15 26 Sun Pick September 26
17 27 Mon Pick September 27
17 28 Tue Pick September 28
15 29 Wed Pick September 29
15 30 Thu Pick September 30
15 Dates outside your trip are dimmed.
One row per year, one cell per day. 2006 had 16 rain days, 2009 had 29.
Guam through the year Month High Low Rain days Rainfall Sea January Good 30° 24° 18 days 163mm 29° February Good 30° 24° 13 days 100mm 28° March 31° 24° 15 days 91mm 28° April 31° 25° 16 days 104mm 29° May 32° 25° 17 days 139mm 29° June 31° 25° 19 days 155mm 30° July 31° 25° 22 days 314mm 30° August 31° 25° 23 days 451mm 30° September 31° 25° 24 days 444mm 30° October 31° 25° 24 days 427mm 30° November 31° 25° 20 days 186mm 30° December Good 30° 25° 19 days 121mm 29°
What to pack Loose, light-colored clothes, sandals and a hat did most of the work at 31°C. Sights went in the morning, with a break in the middle of the day.
With rain every other day, a waterproof jacket is a necessity, not extra luggage. One compact umbrella is enough besides.
Common questions Does it rain a lot in Guam in September? Over the past 20 years September averaged 24 rain days (1 mm or more) out of 30. Individual years ran from 16 in the driest to 29 in the wettest.
What should I wear in Guam in September? Days averaged 31°C and nights 25°C. Pack an umbrella, sandals that can get wet, T-shirts, sunscreen plus a hat, a swimsuit, and insect repellent.
Can you swim in Guam in September? Sea surface temperature averaged 29.9°C in September, warm enough to stay in for a long swim. Year to year it ranged 29.6-30.2°C. Check local flags for waves and jellyfish on the day.
Is September a good time to visit Guam? On warmth and rain days alone, Guam's easiest months were December to February. September ranked 6 of 12.
Is Guam humid in September? Mean relative humidity was 84%, with about 30 muggy days (dew point of 20°C or more) in the month.
Previous month Guam in August Next month Guam in October Whole year Guam weather by month Where to go September Compare Compare with Saipan Compare Compare with Honolulu