This page made possible by the sponsorship of: Deerfield Observatory
State College PA

State College
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the State College clear sky chart from 2005-11-05 to 2017-09-10.

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
35%
15038
17%
46822
10%
14998
43%
14998
20%
31279

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
18%
717
13%
2446
6%
716
27%
716
10%
1777
January16th to endNight
16%
768
15%
2496
5%
768
29%
768
13%
1771
February1st to 15thNight
16%
704
13%
2287
4%
701
27%
701
12%
1610
February16th to endNight
17%
631
18%
1963
5%
631
32%
631
14%
1363
March1st to 15thNight
23%
720
18%
1989
9%
720
33%
720
17%
1415
March16th to endNight
24%
768
19%
2103
8%
768
34%
768
20%
1445
April1st to 15thNight
22%
718
14%
1796
4%
718
28%
718
19%
1316
April16th to endNight
35%
684
19%
1764
7%
684
42%
684
27%
1194
May1st to 15thNight
39%
501
16%
1581
9%
501
46%
501
20%
1083
May16th to endNight
47%
374
17%
1497
16%
374
55%
374
21%
912
June1st to 15thNight
48%
360
16%
1440
16%
360
55%
360
21%
851
June16th to endNight
54%
360
17%
1440
18%
360
61%
360
26%
818
July1st to 15thNight
52%
340
15%
1360
17%
340
56%
340
22%
804
July16th to endNight
63%
517
17%
1548
16%
484
66%
484
33%
893
August1st to 15thNight
63%
539
17%
1609
13%
536
65%
536
33%
975
August16th to endNight
63%
708
23%
1854
15%
708
64%
708
35%
1173
September1st to 15thNight
53%
700
24%
1750
13%
700
57%
700
33%
1128
September16th to endNight
50%
657
22%
1823
17%
657
54%
657
29%
1181
October1st to 15thNight
44%
660
20%
1980
16%
660
51%
660
25%
1264
October16th to endNight
31%
704
20%
2112
11%
704
43%
704
21%
1389
November1st to 15thNight
39%
700
20%
2256
15%
700
48%
700
24%
1399
November16th to endNight
25%
720
16%
2520
9%
720
35%
720
13%
1733
December1st to 15thNight
23%
720
12%
2520
6%
720
32%
720
11%
1818
December16th to endNight
19%
768
12%
2688
3%
768
30%
768
10%
1967

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
15%8%36%6%35%5%5%7%32%
47796
Night
14%7%36%5%3445%7%37%
47004
Cloud CoverDay
15%8%36%6%35%5%5%7%32%
47806
Night
14%7%36%5%3445%7%37%
47008
TransparencyDay
49%5%11%20%11%1
47496
Night
45%5%12%22%12%1
46822
SeeingDay
20%12%23%23%14%5%
5522
Night
21%12%25%27%11%1
15042

By Month

Percentage Cloud Cover NE (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
14%9%49%7%5%5%5%35%28%
1489
16th to endDay
13%14%5%8%10%5%6%445%21%
1728
February1st to 15thDay
13%16%6%7%6%26%448%22%
1575
16th to endDay
13%10%5%9%8%45%446%26%
1509
March1st to 15thDay
17%10%47%7%45%447%28%
1957
16th to endDay
16%10%46%5%34346%33%
2121
April1st to 15thDay
17%9%5%5%5%34437%32%
2152
16th to endDay
18%7%35%5%34346%36%
2205
May1st to 15thDay
20%7%35%6%35%447%31%
2367
16th to endDay
16%6%25%6%35%6%5%7%34%
2618
June1st to 15thDay
13%5%36%6%35%5%5%8%35%
2520
16th to endDay
13%5%25%6%35%5%6%9%34%
2520
July1st to 15thDay
10%7%26%6%37%6%6%8%33%
2520
16th to endDay
9%5%36%6%45%6%8%9%35%
2511
August1st to 15thDay
11%5%27%7%46%6%7%9%31%
2340
16th to endDay
13%5%26%5%35%47%9%36%
2336
September1st to 15thDay
17%5%24434446%41%
2098
16th to endDay
16%6%25%42435%6%41%
1805
October1st to 15thDay
17%7%26%425%446%38%
1650
16th to endDay
17%8%37%5%25%45%5%34%
1760
November1st to 15thDay
10%6%36%6%35%5%5%6%39%
1599
16th to endDay
20%9%45%5%35%45%5%28%
1440
December1st to 15thDay
16%12%6%9%7%35%446%23%
1440
16th to endDay
19%13%48%6%35%6%46%20%
1536
January1st to 15thNight
16%9%5%8%8%35%6%5%7%24%
2446
16th to endNight
13%10%5%7%6%45%45%6%29%
2496
February1st to 15thNight
14%10%47%7%25%5%5%7%29%
2285
16th to endNight
12%8%47%7%35%5%45%34%
1963
March1st to 15thNight
16%8%46%435%45%6%35%
1977
16th to endNight
16%7%25%6%23446%39%
2103
April1st to 15thNight
16%11%47%5%33445%34%
1796
16th to endNight
16%5%245%24447%41%
1764
May1st to 15thNight
18%6%25%5%25%446%38%
1581
16th to endNight
11%6%3443446%9%41%
1495
June1st to 15thNight
12%5%344145%5%9%41%
1440
16th to endNight
11%3244345%6%11%42%
1440
July1st to 15thNight
9%4245%35%47%8%43%
1440
16th to endNight
8%325%435%5%6%10%45%
1655
August1st to 15thNight
7%5%24425%47%9%45%
1620
16th to endNight
11%42442445%7%48%
1854
September1st to 15thNight
15%424324347%47%
1750
16th to endNight
14%5%245%34447%44%
1823
October1st to 15thNight
17%5%25%423447%42%
1980
16th to endNight
17%7%2442445%6%39%
2112
November1st to 15thNight
12%7%35%5%24346%43%
2256
16th to endNight
19%8%36%5%35%446%32%
2520
December1st to 15thNight
18%9%38%5%35%5%5%7%27%
2520
16th to endNight
16%10%47%6%45%6%5%7%25%
2688

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
14%9%5%9%7%5%7%435%28%
1489
16th to endDay
13%14%5%10%8%5%5%445%21%
1728
February1st to 15thDay
14%16%6%7%6%35%448%23%
1575
16th to endDay
13%11%5%10%7%44445%27%
1509
March1st to 15thDay
16%11%46%7%35%446%28%
1968
16th to endDay
16%10%46%5%34446%33%
2120
April1st to 15thDay
18%8%46%5%34347%32%
2152
16th to endDay
18%7%35%434346%36%
2205
May1st to 15thDay
20%8%35%6%25%447%31%
2367
16th to endDay
16%6%25%5%35%5%5%8%34%
2618
June1st to 15thDay
13%6%36%6%35%5%6%7%35%
2520
16th to endDay
13%5%25%5%45%5%6%10%34%
2520
July1st to 15thDay
11%7%36%6%45%6%6%8%33%
2520
16th to endDay
9%6%26%5%46%7%7%9%34%
2511
August1st to 15thDay
11%6%27%7%46%6%7%8%31%
2340
16th to endDay
13%5%25%5%35%46%8%37%
2336
September1st to 15thDay
17%6%25%4245%46%40%
2098
16th to endDay
15%7%25%424446%42%
1805
October1st to 15thDay
18%6%35%425%446%38%
1650
16th to endDay
17%9%36%5%34446%33%
1760
November1st to 15thDay
11%6%36%6%35%5%5%6%39%
1599
16th to endDay
20%10%45%6%245%5%5%28%
1440
December1st to 15thDay
17%12%6%9%7%35%445%23%
1440
16th to endDay
18%14%47%6%446%5%6%20%
1536
January1st to 15thNight
15%10%5%8%7%35%6%5%7%24%
2446
16th to endNight
13%11%47%6%45%45%6%29%
2496
February1st to 15thNight
14%10%47%6%35%5%5%6%29%
2278
16th to endNight
12%9%37%7%35%5%45%34%
1963
March1st to 15thNight
16%8%46%5%3435%6%35%
1989
16th to endNight
16%8%25%5%24346%39%
2103
April1st to 15thNight
17%10%5%6%5%24446%33%
1796
16th to endNight
15%6%25%5%235%47%41%
1764
May1st to 15thNight
17%7%25%5%26%446%38%
1580
16th to endNight
12%6%2442446%9%41%
1495
June1st to 15thNight
13%5%24425%5%5%9%41%
1440
16th to endNight
11%3245%245%6%11%42%
1440
July1st to 15thNight
9%4245%35%47%8%42%
1440
16th to endNight
8%3244445%5%11%44%
1655
August1st to 15thNight
6%5%25%5%245%7%8%45%
1620
16th to endNight
10%42442345%7%48%
1854
September1st to 15thNight
15%423324337%48%
1750
16th to endNight
14%5%25%5%34446%44%
1823
October1st to 15thNight
16%5%15%5%23348%42%
1980
16th to endNight
18%6%25%42445%6%39%
2112
November1st to 15thNight
12%7%25%5%24347%43%
2256
16th to endNight
19%8%46%5%34446%32%
2520
December1st to 15thNight
18%9%37%5%35%5%5%7%27%
2520
16th to endNight
16%10%47%6%36%5%5%6%25%
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
57%5%13%15%7%
1490
16th to endDay
64%410%14%5%
1728
February1st to 15thDay
60%411%16%6%1
1577
16th to endDay
56%411%18%7%
1509
March1st to 15thDay
56%411%19%7%
1968
16th to endDay
51%410%21%11%1
2121
April1st to 15thDay
51%48%19%13%1
2152
16th to endDay
47%47%19%17%3
2205
May1st to 15thDay
52%5%9%20%11%1
2367
16th to endDay
47%6%13%18%11%2
2622
June1st to 15thDay
45%6%11%22%13%
2520
16th to endDay
42%7%15%22%11%1
2520
July1st to 15thDay
45%8%10%18%14%2
2371
16th to endDay
39%7%13%23%14%
2355
August1st to 15thDay
45%7%12%21%12%
2327
16th to endDay
41%7%8%25%14%2
2336
September1st to 15thDay
42%5%9%22%17%1
2098
16th to endDay
42%47%22%20%2
1805
October1st to 15thDay
46%5%11%21%14%1
1650
16th to endDay
50%5%11%23%8%
1760
November1st to 15thDay
43%5%12%20%13%4
1599
16th to endDay
55%5%11%19%8%
1440
December1st to 15thDay
60%5%14%14%4
1440
16th to endDay
62%5%12%14%4
1536
January1st to 15thNight
56%5%12%16%8%1
2446
16th to endNight
53%313%18%9%
2496
February1st to 15thNight
51%5%13%19%8%
2287
16th to endNight
50%49%23%11%
1963
March1st to 15thNight
49%5%11%22%10%
1989
16th to endNight
46%411%21%14%1
2103
April1st to 15thNight
52%39%19%13%1
1796
16th to endNight
42%49%23%16%4
1764
May1st to 15thNight
46%6%10%20%14%1
1581
16th to endNight
39%7%14%20%14%2
1497
June1st to 15thNight
38%6%13%27%14%
1440
16th to endNight
34%6%13%28%15%1
1440
July1st to 15thNight
38%7%12%24%14%2
1360
16th to endNight
31%6%17%25%16%2
1548
August1st to 15thNight
33%7%16%23%18%
1609
16th to endNight
34%6%10%27%18%3
1854
September1st to 15thNight
36%5%10%26%18%2
1750
16th to endNight
39%49%25%19%2
1823
October1st to 15thNight
40%5%13%23%15%1
1980
16th to endNight
44%412%27%11%
2112
November1st to 15thNight
41%313%22%14%4
2256
16th to endNight
51%410%19%11%1
2520
December1st to 15thNight
54%6%13%17%7%
2520
16th to endNight
56%5%14%17%5%
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
27%28%24%8%8%1
69
16th to endDay
33%20%30%13%2
96
February1st to 15thDay
26%27%35%10%
90
16th to endDay
25%22%29%20%2
168
March1st to 15thDay
28%18%24%23%5%
270
16th to endDay
21%17%30%19%6%4
288
April1st to 15thDay
24%18%24%21%9%1
270
16th to endDay
22%12%24%17%16%6%
270
May1st to 15thDay
31%18%18%14%12%4
288
16th to endDay
20%11%26%19%16%5%
331
June1st to 15thDay
17%13%23%27%14%2
315
16th to endDay
16%9%30%27%11%3
315
July1st to 15thDay
16%7%27%26%13%7%
305
16th to endDay
11%5%21%29%21%9%
326
August1st to 15thDay
13%421%24%24%11%
313
16th to endDay
12%416%26%21%18%
332
September1st to 15thDay
16%7%18%22%23%11%
294
16th to endDay
20%5%16%23%23%10%
254
October1st to 15thDay
22%6%17%25%21%5%
255
16th to endDay
24%14%26%27%6%
272
November1st to 15thDay
17%10%23%31%15%2
217
16th to endDay
18%20%35%16%10%
60
December1st to 15thDay
21%26%23%16%8%3
60
16th to endDay
32%25%28%14%
64
January1st to 15thNight
24%20%29%20%4
720
16th to endNight
23%20%33%20%1
768
February1st to 15thNight
26%19%31%21%1
704
16th to endNight
24%21%32%20%2
631
March1st to 15thNight
25%15%30%24%3
720
16th to endNight
22%16%29%22%7%
768
April1st to 15thNight
25%16%32%19%5%
718
16th to endNight
22%11%25%29%10%
684
May1st to 15thNight
21%8%23%33%12%
501
16th to endNight
16%7%21%31%21%1
375
June1st to 15thNight
15%6%21%37%19%
360
16th to endNight
12%322%44%16%
360
July1st to 15thNight
12%322%40%20%1
340
16th to endNight
8%315%45%25%1
517
August1st to 15thNight
10%216%43%24%3
539
16th to endNight
13%313%33%31%4
708
September1st to 15thNight
17%5%17%30%24%3
700
16th to endNight
17%6%19%24%28%4
657
October1st to 15thNight
20%9%19%27%19%2
660
16th to endNight
22%16%23%30%6%
704
November1st to 15thNight
18%10%26%31%11%1
700
16th to endNight
26%18%22%23%6%1
720
December1st to 15thNight
28%16%27%23%5%
720
16th to endNight
26%19%29%23%2
768
Page generated at 2017-09-11 19:35:32. Version ac04

Copyright 2017 A. Danko


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