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 2018-03-11.

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%
15766
17%
49140
10%
15726
43%
15726
20%
32790

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
19%
777
13%
2651
6%
776
29%
776
11%
1900
January16th to endNight
17%
832
15%
2704
5%
832
29%
832
13%
1913
February1st to 15thNight
16%
764
13%
2482
4%
761
27%
761
11%
1771
February16th to endNight
19%
683
17%
2125
5%
683
32%
683
14%
1488
March1st to 15thNight
23%
764
18%
2111
9%
764
33%
764
17%
1493
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%
720
24%
1800
13%
720
57%
720
33%
1165
September16th to endNight
53%
717
24%
1990
19%
717
57%
717
31%
1258
October1st to 15thNight
44%
720
19%
2160
15%
720
51%
720
24%
1391
October16th to endNight
33%
768
21%
2304
13%
768
44%
768
22%
1504
November1st to 15thNight
40%
760
20%
2449
15%
760
49%
760
24%
1520
November16th to endNight
27%
780
17%
2730
11%
780
38%
780
14%
1841
December1st to 15thNight
23%
780
12%
2730
5%
780
32%
780
11%
1966
December16th to endNight
20%
832
12%
2912
4%
832
31%
832
10%
2116

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%
49479
Night
14%7%36%5%3445%7%37%
49322
Cloud CoverDay
15%8%36%6%35%5%5%7%32%
49489
Night
14%7%36%5%3445%7%37%
49326
TransparencyDay
49%5%11%20%11%1
49179
Night
45%5%12%22%13%1
49140
SeeingDay
20%12%24%22%14%5%
6082
Night
20%12%24%28%12%1
15770

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%46%28%
1614
16th to endDay
12%14%6%8%9%5%6%45%5%22%
1872
February1st to 15thDay
14%15%6%8%6%36%348%22%
1710
16th to endDay
15%9%5%9%7%45%446%26%
1633
March1st to 15thDay
16%10%47%7%45%447%28%
2072
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%25%434446%40%
2160
16th to endDay
14%6%25%42435%6%43%
1968
October1st to 15thDay
18%7%26%425%346%38%
1800
16th to endDay
16%8%36%5%25%45%5%35%
1920
November1st to 15thDay
11%6%36%6%35%5%5%6%38%
1736
16th to endDay
19%9%35%5%35%46%5%30%
1560
December1st to 15thDay
16%12%6%9%6%35%446%23%
1560
16th to endDay
18%13%48%6%45%6%46%20%
1664
January1st to 15thNight
15%9%47%7%35%6%5%7%26%
2651
16th to endNight
13%10%5%7%6%45%45%6%30%
2704
February1st to 15thNight
14%10%47%7%35%5%5%7%28%
2480
16th to endNight
13%9%47%7%35%5%5%5%33%
2125
March1st to 15thNight
16%8%46%5%3445%6%36%
2099
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%424324447%47%
1800
16th to endNight
13%5%2443445%7%46%
1990
October1st to 15thNight
17%5%25%423447%42%
2160
16th to endNight
17%6%2442445%6%40%
2304
November1st to 15thNight
12%7%25%5%24447%43%
2449
16th to endNight
18%8%36%5%25%45%6%34%
2730
December1st to 15thNight
17%9%38%6%35%5%5%7%27%
2730
16th to endNight
15%10%48%6%45%6%5%7%25%
2912

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
13%9%49%6%5%7%436%28%
1614
16th to endDay
13%15%5%9%8%5%5%445%22%
1872
February1st to 15thDay
14%16%6%7%6%35%448%23%
1710
16th to endDay
15%11%5%9%7%45%445%26%
1633
March1st to 15thDay
16%11%47%6%35%446%28%
2083
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%
2160
16th to endDay
14%6%25%424446%43%
1968
October1st to 15thDay
18%6%36%424446%38%
1800
16th to endDay
16%9%36%5%34446%35%
1920
November1st to 15thDay
11%7%36%6%35%5%5%6%38%
1736
16th to endDay
19%10%45%6%25%5%5%5%30%
1560
December1st to 15thDay
16%12%5%9%7%35%446%24%
1560
16th to endDay
18%14%47%6%45%6%5%6%20%
1664
January1st to 15thNight
15%10%5%8%6%35%6%5%7%26%
2651
16th to endNight
13%11%47%6%35%446%30%
2704
February1st to 15thNight
14%10%48%6%36%5%5%6%28%
2473
16th to endNight
13%10%37%7%35%5%45%33%
2125
March1st to 15thNight
16%8%46%5%2435%6%35%
2111
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%424324437%47%
1800
16th to endNight
13%4245%3445%6%46%
1990
October1st to 15thNight
16%5%15%5%23347%42%
2160
16th to endNight
18%6%25%42445%6%39%
2304
November1st to 15thNight
12%8%25%5%24347%43%
2449
16th to endNight
18%8%46%5%34446%34%
2730
December1st to 15thNight
17%9%37%5%35%5%5%7%27%
2730
16th to endNight
15%10%47%6%36%5%5%7%26%
2912

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
56%5%13%15%8%1
1615
16th to endDay
63%411%14%5%
1872
February1st to 15thDay
60%410%16%5%1
1712
16th to endDay
57%411%18%7%
1633
March1st to 15thDay
55%410%19%8%
2083
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
43%5%9%22%17%1
2160
16th to endDay
40%48%24%20%2
1968
October1st to 15thDay
46%5%10%21%14%1
1800
16th to endDay
48%5%12%24%9%
1920
November1st to 15thDay
44%5%12%20%12%4
1736
16th to endDay
53%5%11%21%8%
1560
December1st to 15thDay
59%5%13%15%5%
1560
16th to endDay
62%5%12%14%4
1664
January1st to 15thNight
55%412%16%9%1
2651
16th to endNight
53%313%19%9%
2704
February1st to 15thNight
52%5%13%19%8%
2482
16th to endNight
51%49%22%11%
2125
March1st to 15thNight
48%5%10%23%11%
2111
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
1800
16th to endNight
37%5%9%26%19%2
1990
October1st to 15thNight
41%5%13%23%15%1
2160
16th to endNight
43%412%27%11%
2304
November1st to 15thNight
40%314%22%14%4
2449
16th to endNight
49%411%21%12%1
2730
December1st to 15thNight
54%6%13%17%8%
2730
16th to endNight
56%5%14%17%5%
2912

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%28%25%10%7%
104
16th to endDay
27%21%32%16%2
144
February1st to 15thDay
25%25%39%10%
135
16th to endDay
29%20%29%17%2
214
March1st to 15thDay
28%21%24%21%4
312
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
17%7%18%22%23%11%
315
16th to endDay
16%7%15%20%26%14%
314
October1st to 15thDay
24%6%16%26%21%5%
315
16th to endDay
22%14%26%26%8%
336
November1st to 15thDay
18%10%22%32%13%1
264
16th to endDay
16%22%36%15%7%1
90
December1st to 15thDay
22%25%26%16%6%2
90
16th to endDay
30%27%30%12%
96
January1st to 15thNight
23%20%30%21%4
780
16th to endNight
24%19%32%21%1
832
February1st to 15thNight
25%19%31%21%1
764
16th to endNight
25%20%31%21%2
683
March1st to 15thNight
25%16%30%24%3
764
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%31%24%3
720
16th to endNight
15%6%18%23%29%6%
717
October1st to 15thNight
20%9%19%27%20%2
720
16th to endNight
22%16%22%30%7%
768
November1st to 15thNight
18%10%25%32%11%1
760
16th to endNight
25%18%22%24%7%1
780
December1st to 15thNight
27%15%27%23%5%
780
16th to endNight
25%19%28%23%2
832
Page generated at 2018-03-12 13:28:08. Version ac04

Copyright 2018 A. Danko


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