Weather forecast for Agios Stefanos, Attica: see the weather today, tomorrow and the day after tomorrow, with temperature, rain and wind at 380 m. Read the daily forecast summary and the next 72 hours in Agios Stefanos for the timing of changing conditions.
Northern Athens, Attica, Greece · 380 m · Kouremenou hill and forest
GFS, ECMWF IFS 9 km / 0,25°, AIGFS, ECMWF AIFS and GEM
Daily minimum and maximum temperature, precipitation, new snowfall in cm, wind and mean
sea-level pressure at the XIONIA weather station location. This is a point forecast for
Agios Stefanos, not a forecast for every part of Athens or Greece.
Agios Stefanos · Model signals, not official warnings.
Weather signals update when the page loads.
Thresholds & official sources
We check the next 72 hours in available model data, without local calibration adjustments. NOAA GFS fallback uses six-hour steps and may include elevation-adjusted temperature. Precipitation and snow use the largest total across complete rolling 24-hour windows; wind and heat use the maximum, frost the minimum. Missing data is not counted as zero. Old or sample data does not produce a current assessment.
XIONIA display thresholds: precipitation ≥20 mm over a complete rolling 24-hour window, fresh snowfall ≥1 cm/24h, wind ≥40 km/h or gusts ≥60 km/h, temperature below 0°C or above 35°C. Thunderstorms require a relevant weather code. One model is sufficient; model counts are not probabilities. Precipitation includes rain and the water equivalent of snow. Complete NOAA 24-hour totals sum four six-hour intervals. NOAA data is not converted into fresh snowfall centimetres. Fresh snowfall is not settled snow depth. Air temperature at 2 m cannot establish road ice or surface frost with certainty.
The signal uses the daily Copernicus / ECMWF Canadian FWI for the selected area’s grid (~8 km), using its own coordinates and date. FWI combines weather and preceding fuel moisture. It is not a station observation, ignition probability or official warning.
1 · Low: FWI < 11.2
2 · Moderate: 11.2 ≤ FWI < 21.3
3 · High: 21.3 ≤ FWI < 38
4 · Very high: 38 ≤ FWI < 50
5 · Extreme / very extreme: FWI ≥ 50
EFFIS has six classes. XIONIA combines the highest two as 5, retaining “very extreme” when FWI > 70. This is our presentation, not a conversion to national warning categories. The same indicative scale is used worldwide, without local vegetation or elevation adjustment. FWI is neither a percentage nor limited to 100. No number is shown without a valid value for today; missing data does not imply low danger.
Start with the 14-day weather forecast. Open the detailed tables to compare models, then explore hourly temperature, precipitation, wind and 850 hPa in the meteogram. Ensembles show the spread of possible outcomes; satellite images show observed clouds.
850 hPa temperature, 2 m temperature and precipitation ensembles for Agios Stefanos, Attica. Choose Open-Meteo or Direct. Auto tries Open-Meteo first, then Direct when unavailable. Direct retains the native time steps of each model; the displayed source and interval apply. Individual member availability varies by model and variable.
Each thin line is a different scenario from the same model. Closely grouped lines show greater agreement; a wider spread shows greater uncertainty. Read temperature and precipitation together, without treating any single member as a certain forecast.
The 850 hPa temperature describes the atmosphere above the surface. It cannot determine snowfall at ground level on its own. Check each model’s update time and source. You can also open the Agios Stefanos ensemble images and meteograms (Greek).
Calibration by source
Local calibration and combination
Active weights appear when the forecast loads.
Open-Meteo
Six model feeds are shown. The default daily high combines GFS, ECMWF IFS 9 km, AIFS and
GEM. The low keeps GFS, ECMWF IFS 0.25°, AIFS and GEM. AIGFS remains visible with zero
default temperature weight. Calibrated precipitation uses GFS, IFS 0.25°, AIFS and GEM,
matching the annual verification. AIGFS precipitation has zero default weight because its
archive is limited. Wind, pressure and the unadjusted baseline keep the original five
feeds.
The September 2025–August 2026 comparison includes 295 / 291 / 305 valid temperature days
at 1 / 3 / 7-day lead times. IFS 9 km improved highs, while IFS 0.25° remained better for
lows. High-temperature seasonal offsets were recalculated; low-temperature offsets were
retained. Temperature from D+8 and precipitation from D+7 have no local correction; these longer horizons were not verified.
Offsets subtract the mean signed error. Today is D+0 and tomorrow D+1. The backtest/skill temperature profiles use the
near-range band through D+3 and the medium-range band through D+7.
Precipitation uses separate bands: D+0–D+2 and D+3–D+6. Final offsets
are fitted values, not independently verified future accuracy. Saved personal settings are
retained; choose the recommended preset and Save to adopt the new defaults.
Daily values require a complete local day for each model and variable. Missing values are
not zero. Pressure is mean sea-level pressure in hPa; wind is at 10 m, not gusts.
Precipitation includes snow water equivalent. Model disagreement is not probability.
Precipitation verification uses 338 common days in September 2025–August 2026. Default
winter multipliers are ×1.30 for D+0–D+2 and ×1.50 for D+3–D+6, applied to the equal
four-model blend. Other seasons and horizons from D+7 use ×1.00. If a required model lacks a
complete day, the default multiplier is skipped.
Expanding-history winter validation reduced MAE from 3.54 to 3.42 mm for 1/3-day offsets
pooled (114 cases, 58 distinct dates), and from 5.64 to 5.52 mm at 7 days (52 dates), with
more false wet-day signals. Final fitted multipliers are not independent future
validation. Personal weights are outside this verification.
New snowfall in cm is the provider’s snowfall field, summed over the local day and
averaged across the available original five feeds. No local snowfall calibration is
applied. Some provider snowfall fields, including ECMWF products, are derived from
precipitation and temperature. Falling snow is not guaranteed settled snow depth; melting
and compaction matter. The precipitation multiplier does not alter snowfall cm.
Icons summarize daily snowfall, precipitation and mean cloud cover, not every hour.
Missing snowfall is shown as —, not zero. Precipitation mm already includes snow water
equivalent.
Available GFS 0.5° / 0.25°, AIGFS 0.25°, ECMWF IFS 0.25°, AIFS 0.25° and ECCC GEM/GDPS 0.15° feeds use six-hour steps. Each available family contributes once per variable. The newest GFS grid is selected, preferring 0.25° for the same cycle. Missing data stays unavailable.
Daily highs, lows and totals use the same daily calculation across the forecast, widget and charts. Six-hour sampling estimates daily extremes. Independent Agios Stefanos calibration is used only after sufficient completed station observations and successful chronological validation, for the exact family set. The calibration status above the forecast states whether independent Direct calibration or a temporary transfer of Open-Meteo corrections is active. A temporary transfer is not independent Direct validation. Unverified AIGFS terrain temperature is excluded when other members are height-adjusted. Where a XIONIA snowfall estimate is shown, its method and conversion factor are stated in the dynamic status. This estimates fresh snowfall, not observed or settled snow depth. Missing data is not counted as zero.
Forecast data:
Open-Meteo
, NOAA, ECMWF and Environment and Climate Change Canada ·
CC BY 4.0
. Processing: XIONIA.
Weather symbols and precipitation types
Drizzle, rain, thunderstorms, mixed rain/snow and snow use available model weather codes
and hourly precipitation. Hail is shown only when a model supplies WMO code 96 or 99;
absence of this code does not rule out hail. Open-Meteo currently provides
thunderstorm-with-hail forecasts only in Central Europe, so this signal is not available
for Greece. A daily symbol summarises weather during the day, not every hour. Simultaneous
liquid precipitation and snow within one model hour is labelled mixed; different hours or
models may indicate a transition instead.
💨 Wind ≥40 km/h or gusts ≥60 km/h · 🥶 Low ≤−5 °C · 🌡️ High ≥35 °C. These are display
thresholds, not official weather warnings. Missing gust forecasts are excluded. Symbols
use the same temperatures as the displayed forecast.
Integrated Forecasting System: the intergovernmental European centre’s numerical model. IFS 9 km and IFS 0.25° are products of the same model family on different data grids.
Global Environmental Multiscale: the atmospheric model within Canada’s GDPS. The current system combines numerical prediction with large-scale guidance from the GEML AI model.
Artificial intelligence ensemble with 31 members. It complements the single AIGFS forecast with alternative scenarios and their spread.
The blend uses the values available for each day and variable. Coverage falls as individual models reach their forecast limits. The two IFS products are not independent models. Model spread shows disagreement, not the probability of a weather event.
Wind: maximum daily speed at 10 m and prevailing direction of origin. Direction uses a speed-weighted circular calculation; missing or strongly opposing directions display a dash. 🥶: low below 0°C. 🥵: high above 30°C. 💨 in Conditions: wind at least 40 km/h or gusts at least 60 km/h.
The choice applies to widgets, maps and forecasts. Actual station readings stay unchanged. Automatic tries Open-Meteo first, then available direct sources if a supported request fails.
Open-Meteo
Data service providing forecasts from NOAA, ECMWF, ECCC, DWD, the Met Office, Météo-France and JMA. Available models, variables and grids depend on the location and product.
Direct model sources
XIONIA collects data directly from the model providers. Forecasts and maps are served after the source cycle has been published and collected. The selected product shows its model, resolution, available variables and run.
How models combine
Each available family contributes once per variable. Direct forecasts select the freshest available GFS grid and use equal family weights as the baseline. Local weights apply only where enabled after validation. The comparison shows actual percentages and model cycles.
Additional model forecasts are also shown for comparison and backtesting. Their presence does not automatically add weight to the combined forecast; check the displayed weights.
Coverage and missing values
A dash means unavailable data. Wind and gust may use different models. AIGFS temperature is excluded when it cannot be compared on the same elevation basis. Six-hour precipitation is water equivalent, not snow depth.
Time window
A “Today” label with hours in parentheses covers only the stated time window; subsequent days require full local coverage. Days 8–14 are a less certain outlook. Agreement between models is not a probability from a true ensemble.
Ensemble forecasts
Ensemble systems provide multiple forecast scenarios; the available systems appear in the chart selector and image catalogue. AIGFS is the single forecast; AIGEFS is the separate ensemble. Available variables and forecast horizons differ by system.
Agios Stefanos and the historic snowfalls of Attica
Agios Stefanos is part of the Municipality of Dionysos in northern Attica, between Parnitha and Penteli and close to Lake Marathon. The XIONIA station is at 380 m. A walk in the town and a trip towards the surrounding hills need their own weather checks: the station is a local reference point, not a measurement for all of Attica.
Station observer Alkis Sarantopoulos recalls the snowy winters of 2002, 2004, 2008 and 2021 in Agios Stefanos. The timeline also includes January 2019 and the 2022 snowfall in Athens and around Mount Hymettus. Each entry identifies its geographical context; the temperatures below belong to the Agios Stefanos station at 380 m.
2002
A snowy winter remembered by the local observer, before the station archive began in 2008.
2004
A snowy winter remembered by the local observer, before the station archive began in 2008.
2008
The station archive begins in 2008. The snowfall that February also marked its all-time minimum temperature in the published record: −6.4 °C on 18 February 2008. Station temperature record.
Agios Stefanos station · 380 m · daily temperature (°C)
Date
Minimum
Maximum
−3.7
−1.1
−6.4
−1.8
−6.2
6.8
Station temperatures before and after, 15–21/2/2008
Agios Stefanos station · 380 m · daily temperature (°C)
The Telemachos episode brought snow to northern and eastern Attica on 7–8 January 2019. The National Observatory of Athens explicitly reported snowfall in Agios Stefanos and nearby northern suburbs. NOA / meteo.gr · 2019.
Instagram posts from Alkis Sarantopoulos’s personal snow archive · publication dates
Medea is one of the snowy winters that stand out in the observer’s local memories. The National Observatory of Athens documented heavy snowfall in Attica on 15–16 February 2021. NOA / meteo.gr · 2021.
Instagram posts from Alkis Sarantopoulos’s personal snow archive · publication dates
Elpis left memorable snowy scenes in central Athens and the areas around Mount Hymettus, as recalled by the observer. The National Observatory of Athens includes the snowfall of 24 January 2022 among the city’s major snow episodes. NOA / meteo.gr · 2022.
Instagram posts from Alkis Sarantopoulos’s personal snow archive · publication dates
The temperature tables above report station measurements. Daily rain-gauge totals do not separate delayed snowmelt from fresh rain in the following days, so no precipitation total is assigned to any snow episode here.
The Instagram dates are publication dates displayed by Instagram, not necessarily the dates the photographs or videos were taken. A precise capture date and location are not documented for every post.