Week of 12 to 18 October 2026: anticyclonic weather after a very warm, dry September. What to measure and with what care
AEMET expects an anticyclonic week in Spain, with temperatures above the usual values and little rain, after a September that Copernicus ranks as the third warmest on record in Europe, with drier air than normal. Four official signals and what to measure for each, starting with relative humidity.
Consulted: 12 October 2026, 06:45 (Madrid time). The forecasts belong to the services cited and may have been updated since.
AEMET, the Spanish meteorological agency, expects an anticyclonic week in Spain, warmer than usual and with little rain, after a September that Copernicus ranks as the third warmest on record in Europe, with drier air than normal. A good week to treat relative humidity with the same care as temperature.
Signals of the week
1. An anticyclonic week, warmer than usual and with little rain. According to AEMET, anticyclonic weather will prevail in Spain throughout the week of 12 to 18 October, and temperatures will recover and reach values above those usual for the time of year. Precipitation will be scarce across the country, although a shower in the far south-east of the peninsula cannot be ruled out. For 19 to 25 October it sees the same pattern as likely, with forecasts subject to a great deal of uncertainty. Source: AEMET, forecast for the weeks from 12 October to 1 November (09/10/2026).
What to measure: maximum and minimum temperature and relative humidity at your site, at your usual interval. With what care: in sunshine, and more so in light wind, a poorly shielded sensor reads high in the middle of the day. Check that the radiation shield is clean, unobstructed and well ventilated; the reasons are in our radiation shield guide.
2. One of Europe's warmest Septembers, with a joint record in the west. According to Copernicus, the average temperature over European land in September 2026 was 1.54 °C above the 1991-2020 average: the third warmest September in the ERA5 data and the joint warmest for western Europe. The largest anomalies, 4 to 6 °C above average, occurred over southern France, Portugal, Spain and parts of Italy. For mainland Portugal, IPMA sums up the month as "Setembro extremamente quente e muito seco" (an extremely hot and very dry September). Source: Copernicus C3S/ECMWF, surface air temperature for September 2026.
What to measure: the September mean from your own record, with the days without data noted. With what care: that anomaly comes from the ERA5 reanalysis and is measured against 1991-2020; it is not your station's. To call it a record month at your site you need a long series, your own or a nearby official station's, and to say which; see what AEMET's record count shows.
3. Drier air than normal across much of Europe. According to Copernicus, in September much of western and central Europe had drier than average conditions in precipitation, surface soil moisture and relative humidity, and precipitation deficits intensified or became more widespread over Iberia. Relative humidity averaged over European land was below the September average for 1991-2020. Source: Copernicus C3S/ECMWF, precipitation, relative humidity, soil moisture and river flow for September 2026.
What to measure: relative humidity at the same time each day, and the dew point, calculated from the temperature and humidity of the same sensor. With what care: relative humidity compares the moisture present with that of saturated air (WMO definition), and that maximum depends on temperature: between warmer and cooler days, the dew point gives a fairer comparison. Accuracy is stated by band, and each sensor has its own: for the logger in the commercial selection, ±2.5 % between 10 % and 90 % (typical) and ±5 % typical outside that band. Flag readings outside the band stated in your own sensor's datasheet.
4. Low rivers in September, the Ebro among them. Copernicus reports below-average river flows across much of Europe in September, including the Ebro, with low flows also in northern Spain. Source: Copernicus C3S/ECMWF, river flow, September 2026.
What to measure: if you log water level or temperature in a river, that the sensor is still submerged and in flowing water. With what care: out of the water, the sensor logs the air; flag that period without mixing it into the series. The data are for September and your catchment may have changed: check on site (our guide to river water temperature).
Checklist
- Radiation shield clean, unobstructed and ventilated.
- Relative humidity: flag readings outside your sensor's accuracy band; dew point for comparing days.
- River sensors: submerged and in flowing water.
- Warnings: AEMET and IPMA.
Limits of this note
This is not an EIC Controls forecast: the forecast is AEMET's, and the September analyses are by Copernicus C3S/ECMWF and IPMA. The Copernicus values come from the ERA5 reanalysis and describe regions, not a specific site.
References
- AEMET (2026). Predicción para las semanas del 12 de octubre al 1 de noviembre de 2026. Aemetblog, 09/10/2026 (accessed 12/10/2026).
- Copernicus Climate Change Service (C3S), ECMWF (2026). Surface air temperature for September 2026. Data: ERA5 (accessed 12/10/2026).
- Copernicus Climate Change Service (C3S), ECMWF (2026). Precipitation, relative humidity, soil moisture and river flow for September 2026 (accessed 12/10/2026).
- IPMA (2026). Boletim Climatológico Portugal, setembro de 2026, Portugal continental (accessed 12/10/2026).
- World Meteorological Organization. OSCAR: Relative humidity (accessed 12/10/2026).
Commercial selection by EIC Controls
To log air temperature and relative humidity at your site, the HOBO data logger with external temperature and relative humidity sensors carries its sensors at the end of a 2 m cable, away from the housing. Its datasheet states an accuracy of ±0.2 °C between 0 and 70 °C and ±2.5 % relative humidity between 10 % and 90 % (typical), with ±5 % typical outside that band, and set-up and download are done over Bluetooth. The installation point and height, the solar radiation shield and how often the data will be downloaded still need to be defined.
Instruments for this application
LI-COR (HOBO, InTemp, LI-COR) · MX2302A
HOBO External Temperature/RH Sensor Data Logger
The HOBO MX2302 is a weatherproof data logger with external temperature and relative humidity sensors. Leveraging Bluetooth Low Energy, the logger enables easy, fast set up and data download directly from your mobile device, and provides high-accuracy…
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