WEATHER FOR BUSINESS

We supply weather data to businesses

Free Weather Plugin

Add this forecast to your website



Local Weather

Butler 14 Day Long Range Forecast

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

Pennsylvania, United States Of America

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

For Butler in the coming two weeks the average daytime maximum temperature will be around 25°C, with a high for the two weeks of 30°C expected on the afternoon of Tuesday 21st. The average minimum temperature will be 14°C, dipping to its lowest on the morning of Saturday 25th at 4°C. Expect the following 14 days ahead to have some days seeing a little precipitation and some days with rain. Current predictions suggest Friday 17th will have the most precipitation with an accumulation of around 9.0mm. On the whole winds are likely to be light.

DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityCloud AmountPrecip AmountWeather
Fri 17
May
04:00

SE
SE

3 / 7 mph 57 / 57°F 97%
Low level cloud: 9%
Mid level cloud: 45%
High level cloud: 100%
Most Significant Cloud Type: medium
75%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

SE
SE

4 / 7 mph 58 / 56°F 97%
Low level cloud: 31%
Mid level cloud: 24%
High level cloud: 16%
Most Significant Cloud Type: low
41%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

S
S

5 / 8 mph 60 / 60°F 96%
Low level cloud: 71%
Mid level cloud: 96%
High level cloud: 38%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

S
S

9 / 11 mph 63 / 62°F 98%
Low level cloud: 96%
Mid level cloud: 100%
High level cloud: 60%
Most Significant Cloud Type: low
100%
Expect 0.2 In of precipitation over the past 3 hours.
0.2 In
16:00

SSW
SSW

7 / 10 mph 63 / 63°F 98%
Low level cloud: 85%
Mid level cloud: 80%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

SSW
SSW

6 / 9 mph 62 / 61°F 98%
Low level cloud: 68%
Mid level cloud: 50%
High level cloud: 100%
Most Significant Cloud Type: low
97%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

SSW
SSW

7 / 10 mph 59 / 59°F 99%
Low level cloud: 99%
Mid level cloud: 75%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sat 18
May
01:00

SSW
SSW

4 / 7 mph 59 / 59°F 99%
Low level cloud: 88%
Mid level cloud: 52%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

SSW
SSW

3 / 5 mph 58 / 58°F 99%
Low level cloud: 98%
Mid level cloud: 45%
High level cloud: 60%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

SSW
SSW

2 / 4 mph 59 / 59°F 99%
Low level cloud: 95%
Mid level cloud: 70%
High level cloud: 9%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SW
SW

3 / 4 mph 62 / 62°F 94%
Low level cloud: 89%
Mid level cloud: 37%
High level cloud: 8%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

NW
NW

4 / 5 mph 77 / 77°F 63%
Low level cloud: 66%
Mid level cloud: 20%
High level cloud: 0%
Most Significant Cloud Type: low
72%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

N
N

4 / 5 mph 76 / 76°F 71%
Low level cloud: 40%
Mid level cloud: 45%
High level cloud: 0%
Most Significant Cloud Type: low
55%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

ENE
ENE

3 / 6 mph 70 / 67°F 90%
Low level cloud: 16%
Mid level cloud: 28%
High level cloud: 0%
Most Significant Cloud Type: low
26%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

SE
SE

3 / 6 mph 61 / 61°F 96%
Low level cloud: 41%
Mid level cloud: 29%
High level cloud: 0%
Most Significant Cloud Type: low
51%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sun 19
May
01:00

SE
SE

3 / 6 mph 57 / 58°F 97%
Low level cloud: 16%
Mid level cloud: 13%
High level cloud: 0%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

ESE
ESE

4 / 7 mph 54 / 54°F 98%
Low level cloud: 34%
Mid level cloud: 6%
High level cloud: 0%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

E
E

3 / 5 mph 59 / 58°F 94%
Low level cloud: 43%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
44%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

E
E

2 / 3 mph 74 / 76°F 69%
Low level cloud: 66%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
67%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

NE
NE

3 / 3 mph 81 / 79°F 52%
Low level cloud: 6%
Mid level cloud: 24%
High level cloud: 0%
Most Significant Cloud Type: medium
39%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

NNW
NNW

3 / 4 mph 81 / 79°F 52%
Low level cloud: 0%
Mid level cloud: 42%
High level cloud: 0%
Most Significant Cloud Type: medium
42%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

NW
NW

4 / 9 mph 73 / 76°F 82%
Low level cloud: 0%
Mid level cloud: 17%
High level cloud: 0%
Most Significant Cloud Type: medium
16%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

N
N

5 / 10 mph 64 / 64°F 95%
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 0%
Most Significant Cloud Type: medium
13%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Mon 20
May
01:00

NE
NE

2 / 5 mph 62 / 62°F 95%
Low level cloud: 0%
Mid level cloud: 11%
High level cloud: 0%
Most Significant Cloud Type: medium
11%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

SE
SE

3 / 6 mph 60 / 60°F 96%
Low level cloud: 3%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
3%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

NE
NE

1 / 2 mph 66 / 63°F 88%
Low level cloud: 11%
Mid level cloud: 10%
High level cloud: 0%
Most Significant Cloud Type: low
14%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SSE
SSE

3 / 3 mph 78 / 78°F 62%
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
13:00

SW
SW

3 / 4 mph 84 / 82°F 48%
Low level cloud: 0%
Mid level cloud: 31%
High level cloud: 0%
Most Significant Cloud Type: medium
30%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

WNW
WNW

3 / 4 mph 84 / 82°F 50%
Low level cloud: 0%
Mid level cloud: 27%
High level cloud: 0%
Most Significant Cloud Type: medium
27%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

NW
NW

2 / 4 mph 76 / 77°F 77%
Low level cloud: 0%
Mid level cloud: 16%
High level cloud: 0%
Most Significant Cloud Type: medium
15%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

ESE
ESE

2 / 4 mph 68 / 68°F 88%
Low level cloud: 0%
Mid level cloud: 7%
High level cloud: 0%
Most Significant Cloud Type: medium
6%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Tue 21
May
01:00

SSE
SSE

3 / 6 mph 64 / 64°F 92%
Low level cloud: 0%
Mid level cloud: 10%
High level cloud: 0%
Most Significant Cloud Type: medium
9%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

SSE
SSE

4 / 9 mph 61 / 61°F 90%
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 0%
Most Significant Cloud Type: medium
13%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

S
S

6 / 9 mph 66 / 64°F 77%
Low level cloud: 0%
Mid level cloud: 16%
High level cloud: 0%
Most Significant Cloud Type: medium
15%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SSW
SSW

7 / 8 mph 78 / 78°F 57%
Low level cloud: 0%
Mid level cloud: 7%
High level cloud: 0%
Most Significant Cloud Type: medium
6%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

SW
SW

7 / 8 mph 85 / 82°F 44%
Low level cloud: 0%
Mid level cloud: 19%
High level cloud: 9%
Most Significant Cloud Type: medium
19%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

SW
SW

9 / 11 mph 84 / 83°F 46%
Low level cloud: 0%
Mid level cloud: 22%
High level cloud: 7%
Most Significant Cloud Type: medium
21%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

SSW
SSW

4 / 8 mph 78 / 78°F 74%
Low level cloud: 0%
Mid level cloud: 6%
High level cloud: 6%
Most Significant Cloud Type: medium
6%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

S
S

3 / 7 mph 69 / 69°F 75%
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 7%
Most Significant Cloud Type: medium
13%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Wed 22
May
01:00

SSE
SSE

5 / 10 mph 66 / 66°F 87%
Low level cloud: 0%
Mid level cloud: 7%
High level cloud: 6%
Most Significant Cloud Type: medium
7%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

S
S

4 / 10 mph 64 / 64°F 87%
Low level cloud: 0%
Mid level cloud: 23%
High level cloud: 25%
Most Significant Cloud Type: medium
23%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

S
S

7 / 11 mph 70 / 67°F 80%
Low level cloud: 0%
Mid level cloud: 17%
High level cloud: 3%
Most Significant Cloud Type: medium
17%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SSW
SSW

12 / 14 mph 81 / 81°F 64%
Low level cloud: 10%
Mid level cloud: 9%
High level cloud: 12%
Most Significant Cloud Type: low
14%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

SW
SW

13 / 17 mph 84 / 85°F 61%
Low level cloud: 4%
Mid level cloud: 45%
High level cloud: 98%
Most Significant Cloud Type: medium
61%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

NNW
NNW

3 / 5 mph 78 / 78°F 86%
Low level cloud: 0%
Mid level cloud: 16%
High level cloud: 100%
Most Significant Cloud Type: medium
19%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
19:00

W
W

2 / 4 mph 77 / 77°F 89%
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 0%
Most Significant Cloud Type: medium
14%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

SE
SE

5 / 10 mph 68 / 68°F 97%
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 0%
Most Significant Cloud Type: medium
14%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
Thu 23
May
01:00

SSW
SSW

9 / 19 mph 67 / 67°F 92%
Low level cloud: 0%
Mid level cloud: 10%
High level cloud: 77%
Most Significant Cloud Type: medium
13%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

SSW
SSW

9 / 16 mph 66 / 66°F 94%
Low level cloud: 11%
Mid level cloud: 46%
High level cloud: 99%
Most Significant Cloud Type: medium
79%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

SSW
SSW

13 / 20 mph 69 / 67°F 88%
Low level cloud: 17%
Mid level cloud: 22%
High level cloud: 12%
Most Significant Cloud Type: low
26%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SW
SW

17 / 20 mph 77 / 78°F 68%
Low level cloud: 18%
Mid level cloud: 6%
High level cloud: 0%
Most Significant Cloud Type: low
19%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

W
W

17 / 20 mph 78 / 78°F 50%
Low level cloud: 0%
Mid level cloud: 28%
High level cloud: 0%
Most Significant Cloud Type: medium
28%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

W
W

15 / 17 mph 72 / 70°F 64%
Low level cloud: 46%
Mid level cloud: 29%
High level cloud: 0%
Most Significant Cloud Type: low
55%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

WNW
WNW

13 / 19 mph 61 / 60°F 77%
Low level cloud: 58%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
58%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

WNW
WNW

10 / 15 mph 59 / 60°F 62%
Low level cloud: 66%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
66%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityCloud AmountPrecip AmountWeather
Fri 24
May
01:00

SW
SW

3 / 6 mph 57 / 58°F 90%
Low level cloud: 1%
Mid level cloud: 12%
High level cloud: 0%
Most Significant Cloud Type: medium
14%
0.0 In
07:00

WNW
WNW

7 / 15 mph 56 / 55°F 79%
Low level cloud: 18%
Mid level cloud: 12%
High level cloud: 0%
Most Significant Cloud Type: low
22%
0.0 In
13:00

SSW
SSW

9 / 18 mph 81 / 81°F 43%
Low level cloud: 0%
Mid level cloud: 10%
High level cloud: 0%
Most Significant Cloud Type: medium
10%
0.0 In
19:00

SE
SE

5 / 10 mph 75 / 78°F 71%
Low level cloud: 0%
Mid level cloud: 10%
High level cloud: 0%
Most Significant Cloud Type: medium
9%
0.0 In
Sat 25
May
01:00

ENE
ENE

3 / 7 mph 62 / 62°F 97%
Low level cloud: 13%
Mid level cloud: 4%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.0 In
07:00

WSW
WSW

4 / 7 mph 51 / 51°F 78%
Low level cloud: 14%
Mid level cloud: 18%
High level cloud: 6%
Most Significant Cloud Type: low
20%
0.0 In
13:00

S
S

5 / 11 mph 83 / 83°F 46%
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
19:00

SE
SE

5 / 11 mph 69 / 69°F 81%
Low level cloud: 0%
Mid level cloud: 26%
High level cloud: 100%
Most Significant Cloud Type: medium
29%
0.0 In
Sun 26
May
01:00

SSE
SSE

6 / 13 mph 68 / 68°F 87%
Low level cloud: 0%
Mid level cloud: 9%
High level cloud: 12%
Most Significant Cloud Type: medium
9%
0.0 In
07:00

SSW
SSW

9 / 19 mph 63 / 63°F 98%
Low level cloud: 99%
Mid level cloud: 91%
High level cloud: 15%
Most Significant Cloud Type: low
100%
0.3 In
13:00

WSW
WSW

10 / 22 mph 79 / 80°F 48%
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 14%
Most Significant Cloud Type: high
13%
0.7 In
19:00

WSW
WSW

4 / 9 mph 73 / 77°F 95%
Low level cloud: 3%
Mid level cloud: 11%
High level cloud: 0%
Most Significant Cloud Type: medium
19%
0.1 In
Mon 27
May
01:00

WSW
WSW

3 / 6 mph 61 / 61°F 94%
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 26%
Most Significant Cloud Type: high
26%
0.0 In
07:00

SW
SW

6 / 12 mph 65 / 65°F 98%
Low level cloud: 97%
Mid level cloud: 14%
High level cloud: 22%
Most Significant Cloud Type: low
100%
0.8 In
13:00

NNW
NNW

5 / 10 mph 70 / 71°F 81%
Low level cloud: 74%
Mid level cloud: 43%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.0 In
19:00

N
N

4 / 8 mph 71 / 71°F 98%
Low level cloud: 73%
Mid level cloud: 43%
High level cloud: 100%
Most Significant Cloud Type: low
99%
0.2 In
Tue 28
May
01:00

N
N

4 / 9 mph 58 / 58°F 98%
Low level cloud: 25%
Mid level cloud: 25%
High level cloud: 3%
Most Significant Cloud Type: low
33%
0.3 In
07:00

NNW
NNW

8 / 17 mph 58 / 57°F 98%
Low level cloud: 92%
Mid level cloud: 50%
High level cloud: 29%
Most Significant Cloud Type: low
100%
0.7 In
13:00

SE
SE

4 / 9 mph 72 / 76°F 69%
Low level cloud: 71%
Mid level cloud: 40%
High level cloud: 41%
Most Significant Cloud Type: low
90%
0.1 In
19:00

NNW
NNW

7 / 15 mph 64 / 64°F 82%
Low level cloud: 0%
Mid level cloud: 21%
High level cloud: 0%
Most Significant Cloud Type: medium
20%
0.0 In
Wed 29
May
01:00

N
N

2 / 5 mph 62 / 62°F 99%
Low level cloud: 100%
Mid level cloud: 57%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.1 In
07:00

NE
NE

4 / 8 mph 60 / 60°F 88%
Low level cloud: 10%
Mid level cloud: 10%
High level cloud: 32%
Most Significant Cloud Type: low
17%
0.0 In
13:00

WNW
WNW

8 / 17 mph 61 / 61°F 81%
Low level cloud: 93%
Mid level cloud: 45%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.0 In
19:00

NNE
NNE

4 / 8 mph 70 / 70°F 74%
Low level cloud: 0%
Mid level cloud: 8%
High level cloud: 0%
Most Significant Cloud Type: medium
8%
0.0 In
Thu 30
May
01:00

SW
SW

4 / 9 mph 57 / 57°F 97%
Low level cloud: 13%
Mid level cloud: 21%
High level cloud: 0%
Most Significant Cloud Type: low
20%
0.0 In
07:00

ESE
ESE

12 / 24 mph 63 / 63°F 82%
Low level cloud: 0%
Mid level cloud: 27%
High level cloud: 4%
Most Significant Cloud Type: medium
26%
0.0 In
13:00

WSW
WSW

10 / 21 mph 69 / 69°F 66%
Low level cloud: 92%
Mid level cloud: 33%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.1 In
19:00

SSE
SSE

11 / 24 mph 60 / 60°F 98%
Low level cloud: 99%
Mid level cloud: 54%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.6 In
Fri 31
May
01:00

E
E

2 / 5 mph 63 / 63°F 94%
Low level cloud: 0%
Mid level cloud: 19%
High level cloud: 5%
Most Significant Cloud Type: medium
18%
0.0 In
07:00

S
S

11 / 22 mph 55 / 52°F 97%
Low level cloud: 99%
Mid level cloud: 70%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.1 In
13:00

SSE
SSE

5 / 10 mph 76 / 78°F 57%
Low level cloud: 0%
Mid level cloud: 23%
High level cloud: 87%
Most Significant Cloud Type: medium
26%
0.0 In
19:00

SW
SW

12 / 25 mph 52 / 47°F 96%
Low level cloud: 98%
Mid level cloud: 78%
High level cloud: 55%
Most Significant Cloud Type: low
100%
0.2 In
Sat 01
Jun
01:00

E
E

10 / 20 mph 60 / 60°F 98%
Low level cloud: 99%
Mid level cloud: 94%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.6 In
07:00

W
W

14 / 29 mph 48 / 42°F 94%
Low level cloud: 100%
Mid level cloud: 31%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.3 In
13:00

W
W

8 / 17 mph 70 / 70°F 81%
Low level cloud: 59%
Mid level cloud: 23%
High level cloud: 0%
Most Significant Cloud Type: low
67%
0.2 In
19:00

W
W

8 / 16 mph 59 / 57°F 79%
Low level cloud: 6%
Mid level cloud: 29%
High level cloud: 22%
Most Significant Cloud Type: medium
47%
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