Rain has been measured on this Rock since 1790, when the Royal Engineers began keeping the record, and 236 years of it reduce to two numbers. December averages 150.7 millimetres of rain. July averages 0.7. Everything else about Gibraltar's weather is detail hung on that contrast. What follows is the month by month picture, the two winds that decide what any given day looks like, the sea temperatures that matter if you intend to swim, and the one month that genuinely catches guests out. Where a figure cannot be sourced properly, this post says so rather than rounding it into something that looks confident. These are the 1991 to 2020 climate normals for the Gibraltar International Airport station, the longest consistent run of published figures for the territory. The Gibraltar Meteorological Office keeps the official record and takes hourly observations of temperature, wind, visibility, cloud, sunshine, rainfall and pressure, but it does not publish its normals as an open table, so the numbers below come from the [airport station normals](https://en.wikipedia.org/wiki/Climate_of_Gibraltar). If you need certified figures for a contract or an insurance claim, request them from the Met Office directly through the [Government of Gibraltar weather service](https://www.gibraltar.gov.gi/new/weather), which also runs a duty forecaster line. |Month|Average high|Average low|Rain|Rain days|Sunshine| |January|16.3C|11.2C|97.5 mm|7.2|147 hours| |February|16.7C|11.5C|93.6 mm|6.4|143 hours| |March|18.3C|12.7C|83.4 mm|6.6|204 hours| |April|20.0C|13.9C|68.8 mm|6.5|233 hours| |May|22.6C|16.0C|26.9 mm|3.7|289 hours| |June|25.6C|18.5C|8.5 mm|0.9|319 hours| |July|28.1C|20.5C|0.7 mm|0.2|326 hours| |August|28.4C|21.2C|1.1 mm|0.2|309 hours| |September|25.9C|19.7C|25.6 mm|2.7|240 hours| |October|22.5C|17.3C|84.9 mm|6.3|197 hours| |November|19.1C|14.1C|99.1 mm|7.3|135 hours| |December|17.0C|12.4C|150.7 mm|7.9|134 hours| Across the year that averages out at a daily high of 21.7C, a daily low of 15.8C, 740.8 millimetres of rain spread over 56 wet days, and 2,676 hours of sunshine. The hottest temperature ever recorded here was 40.6C on 5 July 1994. The coldest was exactly 0.0C on 13 January 1978, which means the record holds no sub zero reading at all. Two independent sources agree, which is worth knowing because Gibraltar weather pages tend to copy each other. The Government of Gibraltar puts the mean August temperature at 24.3C and the mean January temperature at 13.5C. Work the same means out of the airport normals and you get 24.8C and 13.75C. Half a degree apart on a thirty year average is agreement, not conflict. Guests arriving in December expect mild, and mild is correct: the average high is 17.0C and the average low 12.4C, which beats most of Europe. What they do not expect is 150.7 millimetres of rain, the wettest month of the Gibraltar year by a margin of 50 millimetres over second placed November. The trap is not the total. It is the distribution. That 150.7 millimetres falls across an average of 7.9 days. Do the division and a wet December day in Gibraltar delivers around 19 millimetres, which is a proper soaking rather than drizzle. The pattern is a day of heavy rain, then three clear ones. The Government of Gibraltar classes roughly 30 per cent of winter days as wet, so the odds on any single day are in your favour, but a four night December stay has a realistic chance of losing one afternoon entirely. Pack a waterproof and a plan B, and stop worrying about it. Most Mediterranean destinations have one prevailing wind. Gibraltar has two, and they produce completely different days from the same forecast temperature. The Levanter is a warm, humid easterly that funnels through the Strait. [SKYbrary classes it as a mountain gap wind](https://skybrary.aero/articles/levant-wind), strongest when pressure is higher over the Mediterranean than over the Atlantic. The air arrives moist but unsaturated, gets forced up over a 426 metre limestone ridge, condenses at the top and streams west off the summit as a lens shaped banner cloud. It needs a stable cap above it to form, which is why some easterly days produce a spectacular cloud and others produce nothing at all. Here is the part that actually changes your plans. The banner sits over the eastern side of the peninsula and leaves the west clear. All three sandy beaches are on the east. So a grey, clammy morning at Catalan Bay can be a bright one at the marina ten minutes away, and the right move on a Levanter morning is to walk west rather than write the day off. The [full mechanics of the Levanter cloud](/blog/gibraltar-levanter-cloud-explained) are worth reading if you want to predict it. The Poniente is the opposite: a cooler westerly off the Atlantic. Poniente days are the clearest of the year, the summit is visible, and the air feels dry rather than close. If you have one day to go up the Rock, spend it on a Poniente. What nobody publishes is how many Levanter days a year Gibral