San Juan climate: monthly averages: annual mean temperature 26.8 C; warmest month Aug (28.1 C); coldest month Jan (25.2 C).
Annual mean temperature: 26.8 C
Warmest month: Aug (28.1 C)
Coldest month: Jan (25.2 C)
Wettest month: Sep (5.40 mm/day)
All-time record high: 32.7 C
All-time record low: 20.7 C
This page is a single place to check San Juan climate: monthly averages. San runs from 25.2 C in Jan to 28.1 C in Aug, a swing of 2.9 C. Rain is spread through the year, with Sep the wettest month at 5.40 mm/day and Feb the driest at 1.60 mm/day. Taken together that is roughly 1,203 mm of rain a year for the grid cell. Values come from a public open API; a successful result is cached so a later outage never blanks the page. Scroll for the month-by-month figures, or jump to a neighbouring location from the links below.
Annual mean temperature 26.8 C
Warmest month Aug (28.1 C)
Coldest month Jan (25.2 C)
Wettest month Sep (5.40 mm/day)
All-time record high 32.7 C
All-time record low 20.7 C
Annual precipitation 1,204 mm / year
Coordinates 18.46633, -66.10572
Population 418,140
Average monthly temperature and rainfall in San Juan
Month
Mean temp (C)
Rain (mm/day)
Record high (C)
Record low (C)
Jan
25.2
1.65
30.7
20.9
Feb
25.2
1.60
31.4
20.7
Mar
25.5
1.97
32.3
20.9
Apr
26.3
2.55
32.7
21.8
May
27.0
4.16
32.6
22.8
Jun
27.6
3.01
32.5
24.5
Jul
27.9
3.22
32.1
25.1
Aug
28.1
4.18
32.3
25.3
Sep
28.1
5.40
32.5
25.1
Oct
27.6
5.20
32.0
24.6
Nov
26.6
4.56
31.4
23.0
Dec
25.7
2.06
31.4
21.8
What the San Juan climate table shows
Values are multi-decadal climatological averages for the 18.46633, -66.10572 grid cell, not a single year. Rain is the daily mean, so a value of 2.00 mm/day is about 60 mm across a 30-day month. Averages smooth over extremes, so use them for planning rather than for what to pack for next Tuesday.
Frequently asked questions
Why do the numbers differ from a weather app?
An app shows one location on one day. These are long-run averages, so they smooth out single hot or cold spells.
How much rain is 5.40 mm/day in a month?
Rain is recorded as a daily mean, so 5.40 mm/day is roughly 164 mm across a 30-day month.