The warmest places to visit in December in the USA are San Juan, Puerto Rico, with an average high of 84.2 F, Kahului on Maui at 83.3 F and Honolulu at 81.8 F, by NOAA's 1991 to 2020 normals. Puerto Rico and Hawaii are also the only US places in our table where December sea water averages over 76 F.
Our comparison (9 Nov 2026): we lined up NOAA's December normals for 13 US places, plus sea temperatures from NOAA's coastal water guide. Only 3 average 80 F or warmer. Only 6 have sea water of 75 F or warmer. Of those 6, Key West had the fewest rain days, 6.4.
December weather, side by side
Highs and lows are daily averages in December. Rain days are days with 0.01 inch of rain or more. Sea temperature is the December average at the NOAA coastal station named in each section below.
| Place | Average high / low (F) | Rain days | Sea temperature (F) |
|---|---|---|---|
| San Juan, Puerto Rico | 84.2 / 73.3 | 20.2 | 82.2 |
| Kahului, Maui | 83.3 / 65.9 | 10.0 | 76.6 |
| Honolulu, Oahu | 81.8 / 69.2 | 8.9 | 78.3 |
| Hilo, Big Island | 78.8 / 65.7 | 22.3 | 76.9 |
| Miami, Florida | 78.2 / 64.3 | 8.0 | 75.1 |
| Key West, Florida | 77.7 / 68.3 | 6.4 | 75.3 |
| Orlando, Florida | 73.8 / 52.9 | 7.1 | Inland |
| Palm Springs, California | 69.2 / 46.2 | 2.7 | Inland |
| St. Augustine, Florida | 68.9 / 51.3 | 8.4 | 63.3 |
| Phoenix, Arizona | 66.2 / 45.3 | 4.0 | Inland |
| Los Angeles, California | 66.1 / 49.1 | 5.4 | 59.3 |
| San Diego, California | 66.0 / 49.8 | 5.8 | 60.7 |
| Death Valley, California | 65.6 / 41.1 | 1.6 | Inland |
| Cancun, Mexico | 85 / 70 | Not confirmed | Not confirmed |
| Tulum, Mexico | 84 | Not confirmed | Not confirmed |
| Cabo San Lucas, Mexico | 81 | Not confirmed | Not confirmed |
The Mexico highs come from Mexico's national weather service, the SMN, in Celsius. We converted them to Fahrenheit and rounded to the nearest degree.
So, for warm air and warm water together, pick Puerto Rico or Hawaii.
Pick by plan
The best match depends on what you want to do most:
- Swim in warm sea water: San Juan, Honolulu and Maui, with sea water of 76.6 to 82.2 F.
- Beach weather with the fewest rain days: Key West, at 6.4 rain days and a 77.7 F high.
- Walk and sightsee in cool air: Los Angeles, San Diego and St. Augustine, at 66.0 to 68.9 F.
- Hike without summer heat: Death Valley, Phoenix and Palm Springs, with highs of 65.6 to 69.2 F and the fewest rain days.
- Warmest air outside the US: Cancun and Tulum, at about 85 F and 84 F.
So, match the place to the plan, because no single place wins on heat, sea and rain at once.
Puerto Rico is the warmest, and the wettest
San Juan has a December average high of 84.2 F and a low of 73.3 F, at Luis Munoz Marin airport. It has 20.2 rain days. Its total rain is 4.85 inches, so many of those days are short showers. The sea at Culebra, the Puerto Rico station in NOAA's coastal guide, averages 82.2 F in December. That is the warmest sea in this guide.
A US citizen needs no passport for Puerto Rico, says CBP, but needs an ID that TSA accepts.
So, Puerto Rico has the warmest air and sea in the US in December, but expect some rain on most days.
Hawaii: pick the dry side of the island
The three Hawaii stations show how much the side of the island matters:
- Kahului, Maui: 83.3 F high, 65.9 F low, 10.0 rain days, sea 76.6 F at Kahului Harbor.
- Honolulu, Oahu: 81.8 F high, 69.2 F low, 8.9 rain days, sea 78.3 F.
- Hilo, Big Island: 78.8 F high, 65.7 F low, 22.3 rain days, sea 76.9 F at Hilo Bay.
Hilo gets 12.07 inches of rain in December. Honolulu gets 2.18 inches. The Central Pacific hurricane season ends on 30 November, says NOAA.
So, for a dry Hawaii trip in December, stay on the Honolulu or Kahului side, not in Hilo.
Key West and Miami are the warm choice in the lower 48
Key West has a December average high of 77.7 F, a low of 68.3 F and 6.4 rain days. Its sea averages 75.3 F. Miami's airport has a 78.2 F high, a cooler 64.3 F low and 8.0 rain days. The sea at Virginia Key, just off Miami, averages 75.1 F.
So, Key West is the best mainland pick for warm nights and dry days in December.
Orlando and St. Augustine are cool in the evening
Orlando has a December average high of 73.8 F, a low of 52.9 F and 7.1 rain days. It is inland, so there is no sea reading. St. Augustine has a 68.9 F high, a 51.3 F low and 8.4 rain days. Its sea averages 63.3 F.
So, for theme parks or old-town walks in December, bring a jacket for the nights.
Los Angeles and San Diego are for walking, not swimming
Los Angeles has a December average high of 66.1 F at LAX, a low of 49.1 F and 5.4 rain days. The sea at Santa Monica averages 59.3 F. San Diego has a 66.0 F high, a 49.8 F low and 5.8 rain days, and San Diego Bay averages 60.7 F.
We recommend Los Angeles in December for museums and beach walks. We would skip swimming. The water is 19 F colder than in Honolulu.
So, Southern California is a good December city trip, but not a warm beach trip.
Palm Springs, Phoenix and Death Valley are mild and dry
Palm Springs has a December average high of 69.2 F, a low of 46.2 F and 2.7 rain days. Phoenix has a 66.2 F high, a 45.3 F low and 4.0 rain days. Death Valley at Furnace Creek has a 65.6 F high, a 41.1 F low and 1.6 rain days. All three are inland.
So, the desert is the driest choice in December, with good hiking days and cold nights.
Cancun, Tulum and Cabo are warmer than Florida
Mexico's weather service gives Cancun a December normal high of 29.4 C (about 85 F) and a low of 21.0 C (about 70 F). Tulum's normal high is 29.1 C (about 84 F). Cabo San Lucas is 27.4 C (about 81 F). Rain days and sea temperature for these towns are not confirmed.
The State Department lists Quintana Roo, where Cancun and Tulum are, and Baja California Sur, where Cabo is, at Level 2, "Exercise increased caution". Level 2 is the second of four levels.
So, Cancun and Tulum beat every mainland US place on December heat, if you have a passport.
Sources
Sources: NOAA NCEI 1991 to 2020 monthly normals for the 13 US airport and park stations (read 9 Nov 2026); the NOAA NCEI Coastal Water Temperature Guide for December sea averages (read 9 Nov 2026); the SMN 1991 to 2020 normals for Cancun (station 23155), Tulum (23025) and Cabo San Lucas (3005) (read 14 Oct 2026); the State Department Mexico advisory of 29 May 2026; CBP and TSA on ID for Puerto Rico; the National Hurricane Center on season dates. Not confirmed: Mexico rain days and sea temperatures. Averages are 30-year normals for one station, so any single week can be warmer or colder.
