Pittsburg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pittsburg clear sky chart from 2005-11-05 to 2017-12-02.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
42%
16061
22%
47780
15%
16016
50%
16016
28%
29776

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
23%
900
20%
2506
8%
895
33%
895
21%
1709
January16th to endNight
21%
960
19%
2526
6%
960
31%
960
23%
1733
February1st to 15thNight
22%
741
17%
2149
6%
738
31%
738
18%
1495
February16th to endNight
21%
631
19%
1893
6%
631
31%
631
19%
1263
March1st to 15thNight
21%
720
17%
2160
7%
720
30%
720
19%
1462
March16th to endNight
34%
588
17%
1998
12%
588
41%
588
20%
1306
April1st to 15thNight
33%
539
23%
1797
13%
539
48%
539
27%
1056
April16th to endNight
42%
540
22%
1800
17%
540
51%
540
26%
1117
May1st to 15thNight
43%
539
18%
1651
11%
539
50%
539
26%
1067
May16th to endNight
56%
562
20%
1569
15%
561
60%
561
31%
1018
June1st to 15thNight
65%
540
23%
1440
17%
540
68%
540
42%
843
June16th to endNight
72%
540
24%
1440
18%
540
75%
540
45%
812
July1st to 15thNight
70%
510
19%
1360
15%
510
71%
510
40%
812
July16th to endNight
74%
564
24%
1437
21%
531
77%
531
43%
827
August1st to 15thNight
78%
539
23%
1766
27%
536
80%
536
42%
908
August16th to endNight
72%
573
25%
1910
29%
573
75%
573
37%
1045
September1st to 15thNight
64%
540
27%
1800
28%
540
67%
540
31%
1036
September16th to endNight
61%
711
32%
1974
24%
711
66%
711
39%
1145
October1st to 15thNight
55%
720
31%
2070
23%
720
61%
720
37%
1194
October16th to endNight
38%
768
29%
2367
19%
768
50%
768
30%
1408
November1st to 15thNight
42%
760
29%
2471
22%
760
53%
760
33%
1380
November16th to endNight
32%
780
26%
2535
17%
780
44%
780
26%
1513
December1st to 15thNight
27%
836
17%
2473
10%
836
35%
836
19%
1716
December16th to endNight
21%
960
19%
2688
6%
960
33%
960
20%
1911

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
12%6%25%5%3445%7%42%
48675
Night
13%5%24424446%45%
47957
TransparencyDay
40%5%11%24%15%2
48356
Night
38%411%24%17%3
47782
SeeingDay
13%7%21%26%21%9%
6043
Night
16%9%25%29%16%2
16063

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
19%6%38%4345%4434%
1432
16th to endDay
11%8%37%6%33345%39%
1695
February1st to 15thDay
13%11%47%4235%45%37%
1711
16th to endDay
11%8%47%5%35%446%36%
1580
March1st to 15thDay
19%7%36%42443438%
1800
16th to endDay
16%9%36%5%35%45%7%33%
2235
April1st to 15thDay
12%5%25%42435%6%45%
2151
16th to endDay
17%6%25%5%2345%6%39%
2160
May1st to 15thDay
17%5%25%5%35%5%6%8%35%
2298
16th to endDay
10%6%25%6%36%5%6%8%39%
2543
June1st to 15thDay
7%3145%36%46%9%46%
2520
16th to endDay
5%325%5%35%5%7%9%46%
2520
July1st to 15thDay
10%4145%35%5%7%9%41%
2520
16th to endDay
42145%36%6%7%11%45%
2631
August1st to 15thDay
6%426%6%35%5%6%10%43%
2182
16th to endDay
8%4145%25%5%6%9%44%
2292
September1st to 15thDay
11%6%25%5%2445%7%44%
2153
16th to endDay
9%42442445%7%51%
1980
October1st to 15thDay
12%5%24423346%50%
1888
16th to endDay
14%414323346%51%
1855
November1st to 15thDay
12%424415%35%5%48%
1717
16th to endDay
17%7%24423235%45%
1755
December1st to 15thDay
18%9%35%5%34346%36%
1521
16th to endDay
16%11%35%424345%37%
1536
January1st to 15thNight
17%7%36%5%3434439%
2506
16th to endNight
13%7%36%425%446%40%
2526
February1st to 15thNight
16%9%37%5%23345%37%
2140
16th to endNight
12%8%36%5%3444440%
1893
March1st to 15thNight
16%7%45%424445%40%
2160
16th to endNight
17%6%25%425%446%39%
1998
April1st to 15thNight
12%6%24433347%47%
1797
16th to endNight
16%5%2432435%7%42%
1800
May1st to 15thNight
15%5%34433447%43%
1651
16th to endNight
7%325%6%45%5%6%9%43%
1568
June1st to 15thNight
7%31442345%8%52%
1440
16th to endNight
4312225%6%6%12%51%
1440
July1st to 15thNight
8%314324447%54%
1440
16th to endNight
5%2145%35%5%7%8%50%
1534
August1st to 15thNight
5%31333445%9%56%
1776
16th to endNight
6%41442346%8%52%
1910
September1st to 15thNight
9%435%42345%6%50%
1800
16th to endNight
10%314323346%54%
1974
October1st to 15thNight
10%3245%23446%52%
2070
16th to endNight
16%5%2432233451%
2367
November1st to 15thNight
11%414313446%52%
2471
16th to endNight
15%5%25%413236%48%
2535
December1st to 15thNight
20%9%44324346%36%
2473
16th to endNight
18%9%45%5%24445%36%
2688

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
52%48%22%10%1
1433
16th to endDay
46%313%27%9%
1695
February1st to 15thDay
48%410%24%10%1
1713
16th to endDay
49%412%20%11%1
1580
March1st to 15thDay
49%49%22%12%1
1800
16th to endDay
50%5%15%21%7%
2237
April1st to 15thDay
38%412%25%17%1
2151
16th to endDay
45%310%26%11%1
2160
May1st to 15thDay
46%6%12%22%11%
2298
16th to endDay
40%7%15%20%12%2
2547
June1st to 15thDay
32%7%13%26%17%2
2520
16th to endDay
31%7%14%22%20%3
2520
July1st to 15thDay
37%7%11%23%15%4
2371
16th to endDay
29%7%17%28%14%1
2466
August1st to 15thDay
34%7%13%26%16%2
2168
16th to endDay
33%7%13%23%18%4
2292
September1st to 15thDay
39%5%8%24%18%4
2153
16th to endDay
32%49%25%23%3
1980
October1st to 15thDay
34%410%26%19%5%
1888
16th to endDay
34%38%30%20%3
1855
November1st to 15thDay
36%5%8%22%19%7%
1717
16th to endDay
42%26%28%16%2
1755
December1st to 15thDay
48%412%21%12%1
1521
16th to endDay
50%213%22%10%1
1536
January1st to 15thNight
47%39%22%16%1
2506
16th to endNight
44%413%23%12%1
2526
February1st to 15thNight
50%38%23%12%1
2149
16th to endNight
45%411%23%13%1
1893
March1st to 15thNight
47%49%19%15%4
2160
16th to endNight
45%5%14%23%10%1
1998
April1st to 15thNight
36%411%25%18%3
1797
16th to endNight
40%48%27%15%3
1800
May1st to 15thNight
41%5%11%25%14%1
1652
16th to endNight
35%9%14%21%15%4
1570
June1st to 15thNight
29%414%26%22%2
1440
16th to endNight
23%6%16%24%21%6%
1440
July1st to 15thNight
31%414%26%16%7%
1360
16th to endNight
26%6%15%32%16%2
1437
August1st to 15thNight
23%6%17%26%23%3
1766
16th to endNight
27%7%13%25%21%5%
1910
September1st to 15thNight
33%5%7%27%18%7%
1800
16th to endNight
30%48%25%24%7%
1974
October1st to 15thNight
31%38%23%26%6%
2070
16th to endNight
37%25%28%20%5%
2367
November1st to 15thNight
31%49%23%23%7%
2471
16th to endNight
39%28%25%21%2
2535
December1st to 15thNight
50%39%20%13%1
2473
16th to endNight
50%410%20%11%2
2688

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
26%15%40%13%31
90
16th to endDay
12%30%41%11%4
96
February1st to 15thDay
15%30%37%13%3
90
16th to endDay
20%19%37%19%2
81
March1st to 15thDay
30%16%34%14%4
90
16th to endDay
18%17%30%23%9%
222
April1st to 15thDay
16%14%31%24%12%
270
16th to endDay
21%8%27%23%14%3
270
May1st to 15thDay
17%12%28%23%14%3
288
16th to endDay
13%5%27%25%17%9%
443
June1st to 15thDay
9%317%28%27%13%
495
16th to endDay
6%423%36%23%5%
495
July1st to 15thDay
14%214%34%22%12%
475
16th to endDay
6%17%27%35%21%
515
August1st to 15thDay
11%18%23%34%21%
335
16th to endDay
12%18%28%31%17%
332
September1st to 15thDay
12%48%23%32%19%
315
16th to endDay
13%210%25%31%17%
314
October1st to 15thDay
11%422%32%21%7%
223
16th to endDay
14%8%34%28%13%
144
November1st to 15thDay
14%11%25%22%19%6%
135
16th to endDay
27%11%31%22%8%
135
December1st to 15thDay
10%13%41%15%12%5%
94
16th to endDay
21%20%42%13%1
96
January1st to 15thNight
22%20%31%21%3
900
16th to endNight
18%17%37%22%2
960
February1st to 15thNight
22%18%31%24%2
741
16th to endNight
18%19%36%24%1
631
March1st to 15thNight
21%17%35%22%3
720
16th to endNight
20%10%30%27%10%
588
April1st to 15thNight
15%13%33%26%9%
539
16th to endNight
19%7%26%30%14%1
540
May1st to 15thNight
15%6%27%34%14%2
540
16th to endNight
8%322%39%23%3
563
June1st to 15thNight
9%116%39%29%3
540
16th to endNight
5%115%46%29%2
540
July1st to 15thNight
10%19%41%32%4
510
16th to endNight
6%18%34%39%10%
564
August1st to 15thNight
7%7%34%41%8%
539
16th to endNight
9%19%34%39%6%
573
September1st to 15thNight
11%411%27%37%8%
540
16th to endNight
12%315%29%30%8%
711
October1st to 15thNight
12%420%33%23%5%
720
16th to endNight
20%6%30%28%12%1
768
November1st to 15thNight
14%7%30%32%13%1
760
16th to endNight
19%13%31%23%11%
780
December1st to 15thNight
24%15%29%23%6%1
836
16th to endNight
22%12%39%22%3
960
Page generated at 2017-12-03 10:16:40. Version ac04

Copyright 2017 A. Danko


Pittsburg Clear Sky Chart |Charts Home