Frostburg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Frostburg clear sky chart from 2005-11-05 to 2017-09-16.

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%
15222
20%
46913
10%
15183
45%
15183
21%
29383

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
15%
716
19%
2351
5%
716
31%
716
11%
1540
January16th to endNight
13%
768
19%
2496
3%
768
31%
768
11%
1640
February1st to 15thNight
17%
704
18%
2287
5%
701
33%
701
13%
1434
February16th to endNight
16%
631
21%
1940
5%
631
34%
631
14%
1273
March1st to 15thNight
23%
720
20%
1980
9%
720
34%
720
18%
1303
March16th to endNight
23%
768
20%
2112
8%
768
32%
768
20%
1384
April1st to 15thNight
23%
718
17%
1823
5%
718
31%
718
21%
1236
April16th to endNight
35%
657
20%
1737
8%
657
42%
657
24%
1153
May1st to 15thNight
39%
540
18%
1620
10%
540
47%
540
21%
1068
May16th to endNight
49%
431
17%
1554
15%
431
54%
431
23%
922
June1st to 15thNight
51%
360
19%
1440
17%
360
60%
360
26%
777
June16th to endNight
51%
360
18%
1440
16%
360
62%
360
26%
785
July1st to 15thNight
54%
406
12%
1426
12%
406
57%
406
25%
857
July16th to endNight
65%
564
18%
1595
13%
531
70%
531
39%
881
August1st to 15thNight
64%
539
19%
1609
14%
536
66%
536
33%
960
August16th to endNight
66%
687
24%
1833
17%
687
67%
687
39%
1092
September1st to 15thNight
54%
720
25%
1803
13%
720
59%
720
36%
1133
September16th to endNight
53%
661
24%
1854
19%
661
57%
661
30%
1172
October1st to 15thNight
42%
660
24%
1980
18%
660
52%
660
27%
1220
October16th to endNight
31%
704
27%
2112
12%
704
50%
704
25%
1254
November1st to 15thNight
35%
700
25%
2193
15%
700
49%
700
23%
1309
November16th to endNight
28%
720
19%
2520
10%
720
42%
720
15%
1602
December1st to 15thNight
23%
720
16%
2520
6%
720
36%
720
12%
1663
December16th to endNight
17%
768
17%
2688
4%
768
33%
768
12%
1725

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
13%7%36%6%35%5%6%7%33%
47829
Night
12%6%25%5%345%6%8%39%
47102
Cloud CoverDay
13%6%36%6%35%5%6%7%35%
47839
Night
13%5%244345%5%7%41%
47106
TransparencyDay
46%312%22%12%1
47536
Night
40%313%25%14%2
46913
SeeingDay
22%11%23%20%14%7%
5535
Night
23%13%21%25%13%1
15227

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
12%7%49%8%5%6%5%5%7%28%
1584
16th to endDay
11%12%5%9%7%36%46%6%26%
1728
February1st to 15thDay
13%11%47%8%35%347%29%
1575
16th to endDay
10%8%410%8%35%46%6%30%
1530
March1st to 15thDay
14%8%46%6%35%446%34%
1969
16th to endDay
16%7%47%5%346%6%8%31%
2112
April1st to 15thDay
13%8%5%7%5%35%5%5%6%33%
2125
16th to endDay
18%7%35%5%2445%6%36%
2232
May1st to 15thDay
20%6%25%5%46%6%5%6%29%
2331
16th to endDay
16%6%35%5%35%5%6%8%33%
2561
June1st to 15thDay
11%5%25%5%35%6%7%10%36%
2520
16th to endDay
10%5%25%5%5%6%6%7%10%32%
2520
July1st to 15thDay
11%6%36%6%46%6%7%8%31%
2445
16th to endDay
8%5%36%6%47%6%8%10%32%
2465
August1st to 15thDay
10%5%36%7%37%7%7%10%28%
2340
16th to endDay
12%425%6%35%7%7%9%35%
2357
September1st to 15thDay
14%6%246%3446%7%39%
2154
16th to endDay
15%7%27%5%345%36%37%
1794
October1st to 15thDay
18%6%24433447%40%
1650
16th to endDay
15%7%26%5%34446%38%
1760
November1st to 15thDay
9%7%35%43445%8%42%
1661
16th to endDay
16%9%35%5%3445%5%34%
1440
December1st to 15thDay
15%8%38%6%45%5%7%7%28%
1440
16th to endDay
15%10%5%8%7%4445%7%26%
1536
January1st to 15thNight
13%6%36%6%36%6%5%8%33%
2351
16th to endNight
12%8%36%6%35%5%5%8%33%
2496
February1st to 15thNight
10%8%35%5%35%5%5%8%37%
2285
16th to endNight
9%7%37%6%47%7%8%7%33%
1940
March1st to 15thNight
14%6%25%5%245%5%9%38%
1968
16th to endNight
15%6%244245%6%6%40%
2112
April1st to 15thNight
12%6%37%5%345%5%7%37%
1823
16th to endNight
15%5%246%3345%7%40%
1737
May1st to 15thNight
18%5%23435%46%8%35%
1620
16th to endNight
13%424435%5%5%8%43%
1552
June1st to 15thNight
9%313436%5%7%9%45%
1440
16th to endNight
10%3144345%6%11%44%
1440
July1st to 15thNight
9%425%5%35%5%7%9%41%
1512
16th to endNight
6%3243346%6%11%46%
1703
August1st to 15thNight
7%4245%345%7%9%44%
1620
16th to endNight
9%41442345%8%51%
1833
September1st to 15thNight
13%42433345%7%48%
1803
16th to endNight
14%5%2343445%7%44%
1854
October1st to 15thNight
17%5%25%42335%7%43%
1980
16th to endNight
14%41342446%8%44%
2112
November1st to 15thNight
12%6%3432445%5%46%
2193
16th to endNight
16%6%35%435%5%5%7%35%
2520
December1st to 15thNight
14%7%35%6%45%6%7%7%30%
2520
16th to endNight
13%9%37%5%245%6%8%33%
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
12%6%38%9%45%5%6%6%30%
1584
16th to endDay
12%10%5%8%6%45%447%28%
1728
February1st to 15thDay
12%11%36%7%5%45%47%31%
1575
16th to endDay
10%7%49%7%35%45%7%33%
1530
March1st to 15thDay
13%8%46%6%3436%5%36%
1980
16th to endDay
15%7%36%6%245%6%7%33%
2111
April1st to 15thDay
12%7%47%5%445%5%6%36%
2125
16th to endDay
18%6%35%5%3345%6%38%
2232
May1st to 15thDay
20%5%26%5%36%5%5%6%31%
2331
16th to endDay
16%5%25%5%345%6%7%35%
2561
June1st to 15thDay
11%4245%35%6%7%9%38%
2520
16th to endDay
10%425%6%37%6%6%10%34%
2520
July1st to 15thDay
11%5%35%6%46%7%7%7%34%
2445
16th to endDay
8%5%36%5%47%7%7%9%34%
2465
August1st to 15thDay
10%5%26%7%47%6%8%9%31%
2340
16th to endDay
12%425%5%46%6%7%9%37%
2357
September1st to 15thDay
14%5%15%5%3445%7%42%
2154
16th to endDay
16%6%26%5%34346%39%
1794
October1st to 15thDay
19%5%2342445%5%42%
1650
16th to endDay
15%5%26%5%25%45%440%
1760
November1st to 15thDay
9%5%36%43345%7%45%
1661
16th to endDay
16%9%25%5%34446%36%
1440
December1st to 15thDay
15%7%37%6%36%5%6%6%30%
1440
16th to endDay
16%10%48%6%35%35%7%27%
1536
January1st to 15thNight
13%6%36%5%36%5%5%8%35%
2351
16th to endNight
12%8%36%5%35%5%5%7%35%
2496
February1st to 15thNight
10%7%35%445%45%7%39%
2278
16th to endNight
9%7%25%5%5%6%5%7%8%35%
1940
March1st to 15thNight
14%5%245%345%5%7%40%
1980
16th to endNight
15%6%344245%5%7%41%
2112
April1st to 15thNight
12%6%27%5%3445%7%39%
1823
16th to endNight
15%5%25%5%3345%6%42%
1737
May1st to 15thNight
18%5%235%245%5%9%36%
1619
16th to endNight
13%4243245%6%7%44%
1552
June1st to 15thNight
10%213335%6%7%8%46%
1440
16th to endNight
10%3144335%6%10%45%
1440
July1st to 15thNight
10%3245%35%5%6%10%42%
1512
16th to endNight
6%3133245%7%10%48%
1703
August1st to 15thNight
7%4145%345%6%9%46%
1620
16th to endNight
9%32342445%7%52%
1833
September1st to 15thNight
12%42432345%6%49%
1803
16th to endNight
16%41342345%7%45%
1854
October1st to 15thNight
17%42442335%7%44%
1980
16th to endNight
14%41432345%8%46%
2112
November1st to 15thNight
13%6%2442345%6%47%
2193
16th to endNight
16%6%25%435%5%5%7%37%
2520
December1st to 15thNight
14%7%35%6%45%5%6%7%32%
2520
16th to endNight
13%7%36%6%35%46%8%35%
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%311%22%9%1
1585
16th to endDay
55%212%19%8%1
1728
February1st to 15thDay
53%213%19%9%
1577
16th to endDay
51%313%22%9%
1530
March1st to 15thDay
49%312%22%10%1
1980
16th to endDay
48%313%21%11%1
2112
April1st to 15thDay
47%212%20%15%1
2125
16th to endDay
46%38%22%15%3
2232
May1st to 15thDay
51%312%19%11%
2331
16th to endDay
45%413%22%10%2
2565
June1st to 15thDay
39%5%14%26%13%
2520
16th to endDay
43%5%15%22%11%1
2520
July1st to 15thDay
46%6%10%20%13%3
2302
16th to endDay
40%413%23%15%1
2310
August1st to 15thDay
45%5%13%23%12%
2327
16th to endDay
40%5%11%26%13%2
2357
September1st to 15thDay
41%310%22%19%2
2154
16th to endDay
47%25%25%17%1
1794
October1st to 15thDay
43%310%28%12%2
1650
16th to endDay
44%28%28%14%1
1760
November1st to 15thDay
37%211%22%20%5%
1661
16th to endDay
49%111%21%14%
1440
December1st to 15thDay
52%313%19%9%1
1440
16th to endDay
55%212%21%8%
1536
January1st to 15thNight
47%312%20%14%2
2351
16th to endNight
47%212%24%11%1
2496
February1st to 15thNight
43%314%23%13%1
2287
16th to endNight
45%312%25%11%
1940
March1st to 15thNight
42%314%28%9%1
1980
16th to endNight
41%313%25%14%1
2112
April1st to 15thNight
44%312%23%15%1
1823
16th to endNight
42%410%22%15%5%
1737
May1st to 15thNight
44%412%23%12%2
1620
16th to endNight
37%5%16%23%14%1
1554
June1st to 15thNight
32%6%15%32%13%
1440
16th to endNight
33%5%16%27%15%1
1440
July1st to 15thNight
38%5%15%24%12%3
1426
16th to endNight
27%5%19%28%15%3
1595
August1st to 15thNight
33%5%15%27%16%1
1609
16th to endNight
31%411%32%18%2
1833
September1st to 15thNight
34%314%24%20%2
1803
16th to endNight
38%39%28%19%
1854
October1st to 15thNight
40%210%29%15%2
1980
16th to endNight
36%110%33%17%1
2112
November1st to 15thNight
38%29%24%19%6%
2193
16th to endNight
45%29%24%14%2
2520
December1st to 15thNight
49%313%22%10%1
2520
16th to endNight
46%317%22%9%
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
36%25%22%5%7%2
85
16th to endDay
37%22%26%11%2
96
February1st to 15thDay
44%25%28%1
90
16th to endDay
31%21%33%13%
144
March1st to 15thDay
30%20%21%22%5%
270
16th to endDay
30%18%26%16%5%3
288
April1st to 15thDay
25%19%21%22%8%1
270
16th to endDay
24%11%26%18%14%5%
270
May1st to 15thDay
36%15%18%13%10%5%
288
16th to endDay
24%10%21%20%11%12%
331
June1st to 15thDay
16%10%26%26%14%6%
315
16th to endDay
15%14%30%19%13%6%
315
July1st to 15thDay
16%6%32%23%14%6%
305
16th to endDay
7%422%31%20%13%
326
August1st to 15thDay
13%6%18%25%22%13%
313
16th to endDay
12%416%26%19%20%
332
September1st to 15thDay
21%5%15%20%23%13%
315
16th to endDay
22%5%19%18%27%7%
257
October1st to 15thDay
26%5%20%21%20%5%
255
16th to endDay
20%17%28%22%10%
272
November1st to 15thDay
20%13%23%23%17%1
214
16th to endDay
33%20%25%13%8%
60
December1st to 15thDay
51%13%16%8%8%1
60
16th to endDay
39%9%39%10%1
64
January1st to 15thNight
33%17%27%17%4
720
16th to endNight
31%22%27%17%1
768
February1st to 15thNight
29%20%26%20%2
704
16th to endNight
26%23%29%18%2
631
March1st to 15thNight
29%18%23%22%5%
720
16th to endNight
26%17%28%19%6%1
768
April1st to 15thNight
23%21%28%20%6%
718
16th to endNight
24%11%21%29%12%1
657
May1st to 15thNight
23%9%19%30%17%
540
16th to endNight
17%8%16%29%22%4
432
June1st to 15thNight
12%6%23%33%22%1
360
16th to endNight
13%423%37%20%1
360
July1st to 15thNight
12%316%38%26%2
406
16th to endNight
7%317%32%34%4
564
August1st to 15thNight
9%311%39%30%4
539
16th to endNight
13%210%36%32%5%
687
September1st to 15thNight
17%5%14%29%27%5%
720
16th to endNight
19%7%13%27%27%4
661
October1st to 15thNight
22%10%19%25%19%3
660
16th to endNight
25%17%22%24%9%
704
November1st to 15thNight
21%16%19%27%13%1
700
16th to endNight
32%13%20%24%7%1
720
December1st to 15thNight
30%16%23%22%6%
720
16th to endNight
30%19%25%20%2
768
Page generated at 2017-09-17 12:05:45. Version ac04

Copyright 2017 A. Danko


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