Fast Forecast

WEATHER FOR BUSINESS

We supply weather data to businesses

Free Weather Plugin

Add this forecast to your website



Local Weather

Slaithwaite 14 Day Long Range Forecast

14 Day weather providing an extended long range forecast outlook for Slaithwaite

Kirklees, United Kingdom

Long range weather outlook for Slaithwaite includes 14 day forecast summary:

Reviewing the forecast for Slaithwaite Over the next 14 days and the average daytime maximum temperature will be around 14°C, with a high for the two weeks of 18°C expected on the afternoon of Sunday 2nd. The mean minimum temperature will be 7°C, dipping to its lowest on the morning of Wednesday 5th at 4°C. The coming 14 days will have some days seeing a little precipitation and some days with rain. Predictions are Monday 10th will have the most precipitation with an accumulation of around 3.0mm. On the whole winds are likely to be moderate.

DayLocal TimeDirSpeed/
Gust		Temp/
Feels Like		HumidityPressureCloud AmountPrecip AmountWeather
Sun 02
Jun		21:00

WNW
WNW

 9 / 13 mph 54 / 50°F 94% 1026 mb
Low level cloud: 57%
Mid level cloud: 45%
High level cloud: 32%
Most Significant Cloud Type: low
76%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Mon 03
Jun		00:00

WNW
WNW

 11 / 15 mph 52 / 49°F 95% 1024 mb
Low level cloud: 69%
Mid level cloud: 13%
High level cloud: 19%
Most Significant Cloud Type: low
75%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

WNW
WNW

 12 / 17 mph 53 / 49°F 94% 1023 mb
Low level cloud: 93%
Mid level cloud: 12%
High level cloud: 98%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

WNW
WNW

 11 / 14 mph 54 / 50°F 93% 1022 mb
Low level cloud: 98%
Mid level cloud: 67%
High level cloud: 75%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

WNW
WNW

 14 / 16 mph 57 / 54°F 86% 1022 mb
Low level cloud: 93%
Mid level cloud: 16%
High level cloud: 33%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

WNW
WNW

 13 / 15 mph 59 / 56°F 80% 1021 mb
Low level cloud: 96%
Mid level cloud: 5%
High level cloud: 16%
Most Significant Cloud Type: low
99%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

WNW
WNW

 14 / 16 mph 59 / 56°F 76% 1020 mb
Low level cloud: 93%
Mid level cloud: 1%
High level cloud: 0%
Most Significant Cloud Type: low
93%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

WNW
WNW

 12 / 13 mph 59 / 55°F 79% 1019 mb
Low level cloud: 61%
Mid level cloud: 1%
High level cloud: 7%
Most Significant Cloud Type: low
61%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

WSW
WSW

 6 / 9 mph 53 / 49°F 97% 1018 mb
Low level cloud: 43%
Mid level cloud: 0%
High level cloud: 31%
Most Significant Cloud Type: low
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Tue 04
Jun		00:00

WSW
WSW

 8 / 13 mph 52 / 49°F 93% 1016 mb
Low level cloud: 43%
Mid level cloud: 0%
High level cloud: 2%
Most Significant Cloud Type: low
42%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

SW
SW

 8 / 13 mph 52 / 49°F 96% 1013 mb
Low level cloud: 76%
Mid level cloud: 20%
High level cloud: 100%
Most Significant Cloud Type: low
95%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

SW
SW

 9 / 13 mph 53 / 49°F 95% 1010 mb
Low level cloud: 91%
Mid level cloud: 100%
High level cloud: 15%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

WSW
WSW

 13 / 18 mph 52 / 48°F 97% 1008 mb
Low level cloud: 95%
Mid level cloud: 70%
High level cloud: 11%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

WSW
WSW

 17 / 21 mph 55 / 50°F 90% 1006 mb
Low level cloud: 44%
Mid level cloud: 56%
High level cloud: 0%
Most Significant Cloud Type: low
63%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

W
W

 19 / 25 mph 52 / 46°F 92% 1005 mb
Low level cloud: 81%
Mid level cloud: 45%
High level cloud: 3%
Most Significant Cloud Type: low
97%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

WNW
WNW

 15 / 18 mph 50 / 44°F 82% 1007 mb
Low level cloud: 27%
Mid level cloud: 15%
High level cloud: 0%
Most Significant Cloud Type: low
32%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

W
W

 8 / 12 mph 46 / 41°F 77% 1009 mb
Low level cloud: 10%
Mid level cloud: 5%
High level cloud: 0%
Most Significant Cloud Type: low
12%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Wed 05
Jun		00:00

WSW
WSW

 6 / 11 mph 41 / 37°F 85% 1011 mb
Low level cloud: 36%
Mid level cloud: 31%
High level cloud: 0%
Most Significant Cloud Type: low
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

WSW
WSW

 7 / 14 mph 40 / 35°F 88% 1011 mb
Low level cloud: 8%
Mid level cloud: 9%
High level cloud: 0%
Most Significant Cloud Type: low
10%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

WSW
WSW

 11 / 13 mph 45 / 39°F 81% 1012 mb
Low level cloud: 19%
Mid level cloud: 10%
High level cloud: 0%
Most Significant Cloud Type: low
21%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

W
W

 15 / 18 mph 51 / 45°F 66% 1012 mb
Low level cloud: 88%
Mid level cloud: 38%
High level cloud: 7%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

W
W

 16 / 19 mph 53 / 47°F 63% 1013 mb
Low level cloud: 54%
Mid level cloud: 46%
High level cloud: 0%
Most Significant Cloud Type: low
70%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

W
W

 16 / 19 mph 54 / 49°F 59% 1014 mb
Low level cloud: 39%
Mid level cloud: 44%
High level cloud: 16%
Most Significant Cloud Type: low
56%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

W
W

 14 / 16 mph 52 / 46°F 73% 1014 mb
Low level cloud: 17%
Mid level cloud: 29%
High level cloud: 32%
Most Significant Cloud Type: low
31%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

WSW
WSW

 9 / 15 mph 47 / 42°F 84% 1015 mb
Low level cloud: 30%
Mid level cloud: 46%
High level cloud: 80%
Most Significant Cloud Type: low
55%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Thu 06
Jun		00:00

SW
SW

 6 / 10 mph 44 / 40°F 92% 1015 mb
Low level cloud: 53%
Mid level cloud: 46%
High level cloud: 18%
Most Significant Cloud Type: low
70%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

SW
SW

 5 / 10 mph 41 / 38°F 95% 1015 mb
Low level cloud: 56%
Mid level cloud: 15%
High level cloud: 47%
Most Significant Cloud Type: low
67%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

SW
SW

 6 / 7 mph 46 / 42°F 87% 1015 mb
Low level cloud: 35%
Mid level cloud: 95%
High level cloud: 64%
Most Significant Cloud Type: low
76%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

WSW
WSW

 10 / 11 mph 53 / 49°F 62% 1015 mb
Low level cloud: 57%
Mid level cloud: 100%
High level cloud: 78%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

SW
SW

 11 / 12 mph 56 / 52°F 56% 1014 mb
Low level cloud: 44%
Mid level cloud: 100%
High level cloud: 16%
Most Significant Cloud Type: low
80%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

WSW
WSW

 10 / 13 mph 51 / 47°F 81% 1013 mb
Low level cloud: 81%
Mid level cloud: 100%
High level cloud: 2%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

SW
SW

 10 / 12 mph 50 / 46°F 83% 1011 mb
Low level cloud: 94%
Mid level cloud: 51%
High level cloud: 4%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

SSW
SSW

 13 / 19 mph 47 / 42°F 94% 1009 mb
Low level cloud: 84%
Mid level cloud: 59%
High level cloud: 0%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
Fri 07
Jun		00:00

SW
SW

 13 / 19 mph 48 / 42°F 97% 1008 mb
Low level cloud: 97%
Mid level cloud: 23%
High level cloud: 5%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

WSW
WSW

 13 / 18 mph 48 / 42°F 95% 1008 mb
Low level cloud: 79%
Mid level cloud: 46%
High level cloud: 1%
Most Significant Cloud Type: low
95%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

WSW
WSW

 11 / 13 mph 48 / 42°F 93% 1008 mb
Low level cloud: 66%
Mid level cloud: 13%
High level cloud: 0%
Most Significant Cloud Type: low
70%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

WSW
WSW

 16 / 19 mph 52 / 46°F 78% 1009 mb
Low level cloud: 71%
Mid level cloud: 46%
High level cloud: 0%
Most Significant Cloud Type: low
86%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

WSW
WSW

 18 / 22 mph 53 / 47°F 77% 1009 mb
Low level cloud: 64%
Mid level cloud: 46%
High level cloud: 0%
Most Significant Cloud Type: low
79%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

W
W

 19 / 24 mph 53 / 47°F 78% 1009 mb
Low level cloud: 52%
Mid level cloud: 9%
High level cloud: 2%
Most Significant Cloud Type: low
55%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

WNW
WNW

 15 / 17 mph 53 / 48°F 70% 1011 mb
Low level cloud: 4%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
4%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

W
W

 10 / 15 mph 47 / 41°F 83% 1012 mb
Low level cloud: 8%
Mid level cloud: 8%
High level cloud: 0%
Most Significant Cloud Type: low
10%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sat 08
Jun		00:00

W
W

 13 / 20 mph 44 / 38°F 86% 1012 mb
Low level cloud: 31%
Mid level cloud: 10%
High level cloud: 0%
Most Significant Cloud Type: low
34%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

W
W

 15 / 24 mph 44 / 36°F 89% 1012 mb
Low level cloud: 44%
Mid level cloud: 13%
High level cloud: 0%
Most Significant Cloud Type: low
48%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

W
W

 18 / 23 mph 46 / 39°F 87% 1012 mb
Low level cloud: 56%
Mid level cloud: 10%
High level cloud: 0%
Most Significant Cloud Type: low
59%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

W
W

 20 / 24 mph 48 / 41°F 86% 1012 mb
Low level cloud: 92%
Mid level cloud: 30%
High level cloud: 3%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

W
W

 25 / 29 mph 50 / 43°F 84% 1012 mb
Low level cloud: 91%
Mid level cloud: 13%
High level cloud: 0%
Most Significant Cloud Type: low
95%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

WNW
WNW

 23 / 29 mph 55 / 49°F 79% 1014 mb
Low level cloud: 83%
Mid level cloud: 14%
High level cloud: 11%
Most Significant Cloud Type: low
89%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

WNW
WNW

 20 / 24 mph 52 / 46°F 86% 1015 mb
Low level cloud: 78%
Mid level cloud: 44%
High level cloud: 0%
Most Significant Cloud Type: low
92%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

WNW
WNW

 17 / 24 mph 49 / 42°F 86% 1017 mb
Low level cloud: 67%
Mid level cloud: 9%
High level cloud: 18%
Most Significant Cloud Type: low
71%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
DayLocal TimeDirSpeed/
Gust		Temp/
Feels Like		HumidityPressureCloud AmountPrecip AmountWeather
Sun 09
Jun		00:00

ENE
ENE

 6 / 9 mph 54 / 52°F 90% 1021 mb
Low level cloud: 9%
Mid level cloud: 12%
High level cloud: 0%
Most Significant Cloud Type: low
13%
0.0 In
06:00

ESE
ESE

 2 / 4 mph 58 / 59°F 84% 1021 mb
Low level cloud: 15%
Mid level cloud: 17%
High level cloud: 47%
Most Significant Cloud Type: low
26%
0.0 In
12:00

SSE
SSE

 4 / 7 mph 70 / 71°F 52% 1024 mb
Low level cloud: 0%
Mid level cloud: 45%
High level cloud: 47%
Most Significant Cloud Type: medium
46%
0.0 In
18:00

WSW
WSW

 9 / 16 mph 60 / 60°F 76% 1015 mb
Low level cloud: 76%
Mid level cloud: 44%
High level cloud: 1%
Most Significant Cloud Type: low
91%
0.0 In
Mon 10
Jun		00:00

WSW
WSW

 5 / 9 mph 52 / 50°F 91% 1018 mb
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 9%
Most Significant Cloud Type: medium
14%
0.0 In
06:00

NW
NW

 9 / 18 mph 47 / 43°F 80% 1008 mb
Low level cloud: 93%
Mid level cloud: 45%
High level cloud: 6%
Most Significant Cloud Type: low
100%
0.0 In
12:00

WNW
WNW

 16 / 33 mph 57 / 54°F 78% 1018 mb
Low level cloud: 45%
Mid level cloud: 12%
High level cloud: 0%
Most Significant Cloud Type: low
49%
0.0 In
18:00

WNW
WNW

 12 / 25 mph 59 / 56°F 72% 1017 mb
Low level cloud: 14%
Mid level cloud: 8%
High level cloud: 0%
Most Significant Cloud Type: low
16%
0.0 In
Tue 11
Jun		00:00

WNW
WNW

 9 / 19 mph 51 / 47°F 95% 1019 mb
Low level cloud: 62%
Mid level cloud: 88%
High level cloud: 67%
Most Significant Cloud Type: low
100%
0.0 In
06:00

S
S

 2 / 3 mph 53 / 53°F 89% 1021 mb
Low level cloud: 60%
Mid level cloud: 99%
High level cloud: 7%
Most Significant Cloud Type: low
94%
0.0 In
12:00

WNW
WNW

 6 / 13 mph 59 / 59°F 65% 1020 mb
Low level cloud: 45%
Mid level cloud: 5%
High level cloud: 32%
Most Significant Cloud Type: low
50%
0.0 In
18:00

WNW
WNW

 10 / 20 mph 58 / 56°F 61% 1020 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 39%
Most Significant Cloud Type: medium
5%
0.0 In
Wed 12
Jun		00:00

WSW
WSW

 4 / 9 mph 51 / 50°F 91% 1021 mb
Low level cloud: 12%
Mid level cloud: 24%
High level cloud: 100%
Most Significant Cloud Type: low
32%
0.0 In
06:00

SSW
SSW

 4 / 8 mph 50 / 50°F 86% 1017 mb
Low level cloud: 75%
Mid level cloud: 46%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.0 In
12:00

WSW
WSW

 6 / 12 mph 62 / 62°F 71% 1018 mb
Low level cloud: 40%
Mid level cloud: 45%
High level cloud: 18%
Most Significant Cloud Type: low
58%
0.0 In
18:00

WNW
WNW

 10 / 22 mph 56 / 53°F 83% 1014 mb
Low level cloud: 78%
Mid level cloud: 27%
High level cloud: 0%
Most Significant Cloud Type: low
87%
0.0 In
Thu 13
Jun		00:00

SW
SW

 5 / 10 mph 51 / 50°F 87% 1014 mb
Low level cloud: 47%
Mid level cloud: 88%
High level cloud: 100%
Most Significant Cloud Type: low
89%
0.1 In
06:00

SW
SW

 4 / 9 mph 53 / 52°F 96% 1012 mb
Low level cloud: 93%
Mid level cloud: 45%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.0 In
12:00

SSW
SSW

 3 / 6 mph 55 / 55°F 92% 1010 mb
Low level cloud: 78%
Mid level cloud: 67%
High level cloud: 7%
Most Significant Cloud Type: low
100%
0.1 In
18:00

WNW
WNW

 13 / 26 mph 57 / 54°F 73% 1012 mb
Low level cloud: 24%
Mid level cloud: 46%
High level cloud: 3%
Most Significant Cloud Type: low
40%
0.0 In
Fri 14
Jun		00:00

W
W

 2 / 4 mph 54 / 55°F 98% 1009 mb
Low level cloud: 89%
Mid level cloud: 50%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.1 In
06:00

SW
SW

 3 / 6 mph 55 / 55°F 90% 1012 mb
Low level cloud: 89%
Mid level cloud: 23%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.0 In
12:00

S
S

 6 / 13 mph 64 / 64°F 70% 1010 mb
Low level cloud: 49%
Mid level cloud: 21%
High level cloud: 27%
Most Significant Cloud Type: low
59%
0.0 In
18:00

WSW
WSW

 2 / 4 mph 58 / 60°F 95% 1008 mb
Low level cloud: 62%
Mid level cloud: 90%
High level cloud: 32%
Most Significant Cloud Type: low
97%
0.1 In
Sat 15
Jun		00:00

SSE
SSE

 6 / 12 mph 58 / 58°F 96% 1008 mb
Low level cloud: 97%
Mid level cloud: 86%
High level cloud: 33%
Most Significant Cloud Type: low
100%
0.0 In
06:00

WSW
WSW

 8 / 17 mph 51 / 47°F 96% 1004 mb
Low level cloud: 85%
Mid level cloud: 73%
High level cloud: 58%
Most Significant Cloud Type: low
100%
0.1 In
12:00

SSW
SSW

 12 / 24 mph 59 / 56°F 97% 1007 mb
Low level cloud: 93%
Mid level cloud: 65%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.1 In
18:00

NNE
NNE

 6 / 12 mph 57 / 56°F 73% 1011 mb
Low level cloud: 97%
Mid level cloud: 73%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.1 In
Sun 16
Jun		00:00

SW
SW

 10 / 21 mph 53 / 50°F 95% 1010 mb
Low level cloud: 28%
Mid level cloud: 0%
High level cloud: 1%
Most Significant Cloud Type: low
28%
0.1 In
06:00

WSW
WSW

 6 / 13 mph 50 / 48°F 89% 1014 mb
Low level cloud: 39%
Mid level cloud: 2%
High level cloud: 2%
Most Significant Cloud Type: low
39%
0.0 In
12:00

SW
SW

 11 / 24 mph 65 / 65°F 60% 1014 mb
Low level cloud: 66%
Mid level cloud: 1%
High level cloud: 99%
Most Significant Cloud Type: low
78%
0.0 In
18:00

WNW
WNW

 7 / 14 mph 61 / 61°F 63% 1015 mb
Low level cloud: 2%
Mid level cloud: 6%
High level cloud: 50%
Most Significant Cloud Type: medium
13%
0.0 In
Mon 17
Jun		00:00

SSW
SSW

 3 / 6 mph 59 / 59°F 81% 1015 mb
Low level cloud: 0%
Mid level cloud: 98%
High level cloud: 20%
Most Significant Cloud Type: medium
98%
0.0 In
06:00

SE
SE

 2 / 5 mph 55 / 56°F 78% 1014 mb
Low level cloud: 62%
Mid level cloud: 22%
High level cloud: 9%
Most Significant Cloud Type: low
70%
0.0 In
12:00

ENE
ENE

 4 / 9 mph 57 / 56°F 96% 1011 mb
Low level cloud: 57%
Mid level cloud: 82%
High level cloud: 100%
Most Significant Cloud Type: low
97%
0.1 In
18:00

S
S

 5 / 10 mph 60 / 60°F 83% 1012 mb
Low level cloud: 40%
Mid level cloud: 69%
High level cloud: 32%
Most Significant Cloud Type: low
67%
0.0 In

The day label given represents the local day relative to the local time for the location you are looking at.
(More Info)

Day

This time is corrected for local time zones and where possible for daylight saving times.
(More Info)

Local Time

The wind direction we use on this page is the direction the wind is coming from, given in a 16 point compass format.
(More Info)

Dir

This refers to the sustained average wind speed, normally averaged over a period of 10 minutes for up to 3 hrs.
(More Info)

Speed/
Gust

Temperature from our forecast perspective are fairly well defined, they are what we would expect to measure in a standard meteorological screen (in other words, shaded and well ventilated) at 2 metres above ground level.
(More Info)

Temp/
Feels Like

The relative humidity is the percent of saturation humidity, generally calculated in relation to saturated vapour density.
(More Info)

Humidity

The value given is a total predicted for the previous 3 hrs and includes the time of the forecast being looked at.
(More Info)

Precip Amount

The total amount of cloud as a percentage is derived from looking at cloud cover throughout the atmosphere and estimating how these combine when looked at from the ground.
(More Info)

Cloud Amount

Here we try to capture the feel of the weather as an image – it will never be perfect but is useful for a quick overview.
(More Info)

Weather

When we measure for forecast air pressure we are normally doing this relative to a certain height and most commonly relative to Mean Sea Level.
(More Info)

Pressure