National Weather Forecast - Phoenix Info
Everyone knows it's "hot" in Phoenix. How hot is of course the question.
The good news is that the weather is fantastic from October to April - when prices are highest, of course. The heat tends to "break" - cool evenings, days in the 80s - about mid-October. The coldest part of the year is usually late December or early January, with highs in the 60s, lows in the 40s. A rare cold streak would be a high in the 50s, low in the upper 20s. Rain is statistically more common in the winter and spring, but with a yearly average of 7 inches, it's rare and does not last long. Daytime can hit the 90s by March - bring a hat and sunscreen to spring training - but the mornings and evenings stay pleasant.
From late April to late September, do not plan strenuous activity outside during the day - it is more than likely to be over 100 degrees. Mornings stay pleasant more of the year than the evening does - it can be 100 well after dark.
In June, the temperatures begin to exceed 110 on a regular basis and it does not cool off in the evening. But it is often very dry (single digit humidity), which makes it mildly more bearable, particularly in the shade, and helps the mornings (low 80s) feel somewhat cool. Beginning usually early to mid-July, the mornings become warmer and more humid. During a heat wave, it might be 95 at 4am. Temperatures still reach over 105 degrees, and monsoon storms make regular afternoon appearances. It may or may not rain, but dust and wind have been known to do a fair amount of damage. Temperatures still regularly reach over 100 in September, but the mornings begin to cool off again.
All that being said, unlike some other very warm locales, Phoenix KNOWS it's hot and everything is accordingly very well air-conditioned. It is probably not possible to find a hotel room or rental car without air conditioning. If you are here to shop, go to museums, eat or sit in the pool, you will be kept comfortably cool. In fact, those who chill easily who are here for business in the summer (anywhere you will be just sitting without much movement) may want a light sweater to go over short-sleeves or sleevless tops. If, on the other hand, you want to play golf or hike, think twice before coming in the summer if you are not used to the heat. It affects some people more than others, and it can make those not used to it physically ill fairly easily.
It should also be noted that the temperature estimates can be adjusted downward several degrees if you are staying on the fringes of Phoenix - Fountain Hills, Cave Creek - up a little higher and away from the asphalt and concrete in the city.
