São Sebastião do Caí weather in May

In May, São Sebastião do Caí sees average daytime highs of 21°C and overnight lows near 12°C, with 136 mm of rain across 10.4 wet days and about 10.5 hours of daylight. It is the 9th-warmest and 12th-wettest month of the year here.

Highs ease over the month, from about 22°C in the first days to 19°C by the end. The sky is clear or mostly clear about 32% of the time in May, and the air most often feels dry.

Daylight stretches from about 10 h 54 min at the start of May to 10 h 18 min by month's end. Set against the rest of the year, May is São Sebastião do Caí's 7th-clearest and 9th-windiest month. For the whole year in context, see São Sebastião do Caí's year-round climate.

Daytime high
21°
9th warmest
Overnight low
12°
5th coldest
Rainfall
136 mm
10.4 wet days
Daylight
10 h 30 min
8:06 AM – 6:37 PM
Cloud cover
60%
7th clearest
Wind
8 km/h
9th windiest
Solar energy
2.85 kWh/m²
Travel score
6.4
out of 10

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 22°C in the first days to 19°C by the end.

A typical May day in São Sebastião do Caí reaches about 21°C in the afternoon and slips back to 12°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 16°C and 26°C. Set against its neighbours, May runs about 4°C cooler than April and about 2°C warmer than June.

10°20°30°151015202531
Avg high (°C)Avg low (°C)
12213
22213
32213
42213
52213
62213
72213
82213
92213
102113
112112
122112
132112
142112
152112
162112
172112
182112
192012
202012
212012
222011
232011
242011
252011
262011
272011
282011
291911
301911
311911

São Sebastião do Caí weather by month

How May compares with the rest of the year at a glance. May is the 9th-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan29° / 19°20917.613.74.7
Feb28° / 19°18016.613.14.8
Mar27° / 18°15415.212.25.8
Apr24° / 15°14211.211.36.6
May21° / 12°13610.410.56.4
Jun19° / 10°14410.310.16.0
Jul19° / 18010.810.36.0
Aug21° / 11°14510.710.96.4
Sep22° / 12°17812.511.86.1
Oct24° / 14°21614.812.76.0
Nov26° / 16°16412.813.56.2
Dec28° / 18°18215.113.95.4

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 32% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 54%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14753
24852
34852
44852
54753
64753
74753
84753
94654
104753
114753
124654
134654
144654
154654
164654
174654
184654
194753
204753
214654
224654
234654
244654
254654
264654
274555
284555
294555
304456
314456

Chance of precipitation in May

Any precipitation

São Sebastião do Caí gets around 136 mm of rain over 10.4 wet days in May, the driest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 33% and peaks near 35% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
135
235
334
434
534
634
734
834
934
1034
1134
1234
1334
1433
1533
1633
1733
1833
1933
2033
2132
2232
2332
2432
2532
2632
2732
2832
2932
3032
3132

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the dry band about 44% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
131292811
232292810
33329289
43430288
53530277
63531277
73631276
83632275
93732264
103832264
113932263
123932263
134032262
144132262
154132252
164231252
174331241
184431241
194630231
204730221
214829211
225028211
235128201
245327191
255327191
265526181
275626171
285626171
295825161
305825161
315925151

Wind in May

Winds average 8 km/h in May.

Across May, daily wind ranges from about 8 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
218calm
228calm
238calm
248calm
258calm
268calm
278calm
288calm
298calm
308calm
318calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 10 h 54 min at the start of May to 10 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 36 minutes over May. Sunrise moves from 7:56 AM to 8:15 AM, and sunset from 6:49 PM to 6:31 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
110.97:566:49
210.87:576:48
310.87:586:47
410.87:586:46
510.87:596:45
610.78:006:45
710.78:006:44
810.78:016:43
910.78:026:42
1010.78:026:41
1110.68:036:41
1210.68:046:40
1310.68:046:39
1410.68:056:39
1510.58:056:38
1610.58:066:37
1710.58:076:37
1810.58:076:36
1910.58:086:36
2010.48:096:35
2110.48:096:35
2210.48:106:34
2310.48:106:34
2410.48:116:33
2510.48:126:33
2610.38:126:32
2710.38:136:32
2810.38:136:32
2910.38:146:31
3010.38:156:31
3110.38:156:31

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 2.85 kWh/m².

For context, solar energy here swings from a low near 2.41 kWh/m² to a high of 6.44 kWh/m² in December across the year — May's 2.85 kWh/m² sits near the bottom.

01234151015202531
Solar energy (kWh/m²)Level
13.3Moderate
23.2Moderate
33.2Moderate
43.2Moderate
53.1Moderate
63.1Moderate
73.1Moderate
83.1Moderate
93.0Moderate
103.0Moderate
113.0Moderate
122.9Moderate
132.9Moderate
142.9Moderate
152.9Moderate
162.8Moderate
172.8Moderate
182.8Moderate
192.8Moderate
202.8Moderate
212.7Moderate
222.7Moderate
232.7Moderate
242.7Moderate
252.6Moderate
262.6Moderate
272.6Moderate
282.6Moderate
292.6Moderate
302.6Moderate
312.6Moderate
Planning a trip in May

Is May a good time to visit São Sebastião do Caí?

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

6.4
Sightseeing
2nd-best month of the year
3.8
Beach & pool
9th-best month of the year

May is a reasonable time to visit São Sebastião do Caí for sightseeing.

What to pack for São Sebastião do Caí in May

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

In May, São Sebastião do Caí sees daytime highs around 21°C and nights near 12°C. Worth packing: rain gear. About 10 days see rain.

rain gear

UV index in São Sebastião do Caí in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in São Sebastião do Caí peaks around January 16 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 20 at about 4 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highModerateHighVery highExtremeJan 16UV 13Jun 20UV 4
UV index (midday)Level
Jan13Extreme
Feb12Extreme
Mar10Very high
Apr8Very high
May5Moderate
Jun4Moderate
Jul4Moderate
Aug5High
Sep8Very high
Oct8Very high
Nov12Extreme
Dec13Extreme

Air quality in São Sebastião do Caí in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in São Sebastião do Caí is worst in September — around 17 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (December, 10 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodSep 1217 µg/m³Dec 1910 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb10Good
Mar10Good
Apr12Good
May12Good
Jun11Good
Jul13Moderate
Aug16Moderate
Sep17Moderate
Oct12Good
Nov11Good
Dec10Good
Location & terrain

Where is São Sebastião do Caí?

São Sebastião do Caí sits at 29.6°S, 51.4°W, 16 m above sea level, in Brazil. The nearest listed city is Montenegro, 14 km away.

Topography around São Sebastião do Caí

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of São Sebastião do Caí.

Within 3 km, the terrain around São Sebastião do Caí has only modest variations in elevation — a maximum elevation change of 107 m around an average of 32 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 512 m; within 80 km, large variations in elevation — a maximum elevation change of 988 m.

The land around São Sebastião do Caí is covered by trees (69%) within 3 km, trees (73%) within 16 km, and trees (62%) within 80 km.

3 km
107 m
16 km
512 m
80 km
988 m
treesgrasslandcroplandartificial surfaceswaterwetland
May weather nearby: Montenegro 14 km · Portão 18 km · Estância Velha 21 km · Ivoti 21 km · Novo Hamburgo 26 km · Dois Irmãos 28 km · São Leopoldo 29 km · Nova Santa Rita 31 km

Brazil travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / N
127 / 220 V · 60 Hz
Prices
≈ 46% of US
price level, 2025
GDP per capita
$10,713
2025
Happiness
6.6 / 10
World Happiness, 2025
Safe drinking water
89%
of population, 2024
Homicide rate
19.3
per 100k, 2023
Road deaths
16
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Low
EF EPI 482
Religion
Roman Catholic 57%Evangelical 27%none 9%other 4%

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 São Sebastião do Caí (-29.5867°, -51.3756°, elevation 16 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. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).