Weather clocks
A weather clock does three jobs on one display: it tells the time, it shows the temperature indoors and out, and it gives you a forecast based on the air pressure it is measuring at your own address. Most models pair the display with a small wireless sensor you put outside, so you get the real outdoor temperature while standing in the kitchen.
The range runs from a compact bedside unit to colour displays with barometric pressure graphing and multiple sensors. For clocks without weather functions see wall clocks and the full clock range; for full measurement including rainfall and wind see home weather stations.
What a weather clock gives you
The forecast icon on a weather clock is not downloaded from anywhere. The instrument measures barometric pressure, watches how it changes over the preceding hours, and applies a simple rule: falling pressure means deteriorating conditions, rising pressure means improvement, steady pressure means more of the same.
That sounds crude, and over a twelve-hour horizon it is surprisingly good — because it is measuring your location rather than a regional average. It will tell you that the pressure is dropping quickly at your house, which a national forecast covering three counties cannot. It will not tell you what next weekend holds, and no instrument of this type will.
The outdoor temperature is the other half of the value, and for most owners it is the part they use daily. A wireless sensor mounted in a shaded spot outside sends the reading indoors, so you know whether it is actually cold before you open the door.
Bedside and compact models
At the smaller end, the Bresser round digital alarm clock with indoor temperature is a simple bedside unit. The Technoline WS 9767 adds a wireless outdoor sensor and an alarm, and the WS9140 presents indoor and outdoor temperature in a clock-first layout.
The TFA Ratio wireless min and max thermometer with clock is worth singling out because it records highs and lows. Knowing that it dropped to minus two overnight is considerably more useful than knowing it is four degrees now, particularly for gardeners and anyone watching for frost.
Forecast stations with alerts
The middle of the range is where the forecast function gets useful. The Bresser Meteo Temp W with ice alert warns you when the outdoor temperature approaches freezing, which is the single most practical alert on any of these instruments. The Technoline WS 9130 and WS 9136 are straightforward forecast stations, and the WS 9132 adds barometric pressure and a frost alert.
The Bresser 7007620 radio-controlled colour weather station presents the same information in colour with a framed display, and the Bresser Neomeo H adds an indoor comfort indicator that flags when a room's temperature and humidity combination is likely to cause condensation or feel stuffy.
Models with pressure graphing
If you want to read the trend yourself rather than trust an icon, you want a pressure graph. The Bresser ClimateTemp NDH-NEO and NDV-NEO both plot barometric pressure history, so you can see the shape of an approaching system rather than a symbol summarising it.
The ACCUR8 YD8230A is the most complete instrument in this part of the range, combining MSF radio-controlled time, a barometric pressure graph, indoor and outdoor temperature and humidity, and sunrise and sunset times. The Technoline WS 6440 takes a different approach with a colour LED display designed to be read at a glance from across a room.
Projection and connected models
The Bresser 7004405 projection radio-controlled weather station projects the time and temperature onto a ceiling while functioning as a full forecast station, which suits a bedroom where you would otherwise want two devices. See projection clocks for more on projection.
The Mobile-Alerts MA10901 forecast station is the one to look at if you want your readings on a phone. With the optional internet gateway it uploads to the Mobile-Alerts service, so you can check conditions at home from anywhere and add further sensors to the same system over time.
Siting the outdoor sensor
This is the difference between a weather clock that is accurate and one you stop trusting. The sensor must be in shade. Direct sunlight on a small plastic sensor housing can add three to five degrees, and every winter we speak to customers convinced their sensor is faulty when it is simply mounted on a sunlit wall.
A north-facing wall is ideal, under an overhang or eaves so rain does not sit on it, with clear air around it. Avoid mounting above a window, near a vent or extractor, above a patio that stores heat, or against a wall that bakes all afternoon. Keep it within the stated transmission range and remember that each wall between sensor and display cuts that range.
Use lithium batteries in the outdoor sensor. Alkaline cells lose capacity sharply below freezing, and a sensor that drops out on the coldest night of the year is the classic symptom.
Setting up the forecast
Give a new weather clock two or three days before judging its forecast. The pressure trend function needs a history to work from, and until it has one the icon is little better than a guess. If the instrument lets you enter your altitude, do so — pressure corrected to sea level will match published readings, while an uncorrected instrument a hundred metres up reads consistently low.
Related ranges
For rainfall and wind measurement as well, see home weather stations and complete home weather stations. For pressure instruments on their own, see digital barometers and the full barometer range. For clocks without weather functions, see wall clocks, radio controlled clocks and the complete clock range. Weather clocks make a reliable present, and more ideas are in weather gifts and gadget gifts.