Brownington State Wildlife Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brownington State Wildlife Area clear sky chart from 2005-11-05 to 2017-09-23.

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
43%
15864
23%
47015
15%
15817
51%
15817
31%
28387

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
28%
900
22%
2327
8%
895
38%
895
30%
1478
January16th to endNight
28%
960
25%
2496
9%
960
37%
960
30%
1616
February1st to 15thNight
25%
880
18%
2288
6%
876
32%
876
24%
1580
February16th to endNight
25%
660
24%
1922
8%
660
36%
660
28%
1201
March1st to 15thNight
30%
540
22%
1980
13%
540
42%
540
22%
1214
March16th to endNight
29%
576
15%
2112
10%
576
37%
576
18%
1379
April1st to 15thNight
38%
539
22%
1824
14%
539
51%
539
28%
1055
April16th to endNight
35%
540
21%
1775
15%
540
48%
540
24%
1127
May1st to 15thNight
41%
539
19%
1620
14%
539
49%
539
26%
1045
May16th to endNight
49%
563
19%
1604
15%
561
54%
561
30%
1006
June1st to 15thNight
65%
540
21%
1440
15%
540
69%
540
44%
819
June16th to endNight
67%
540
26%
1440
17%
540
71%
540
50%
782
July1st to 15thNight
69%
510
19%
1491
17%
510
70%
510
41%
824
July16th to endNight
75%
564
25%
1594
26%
531
78%
531
46%
831
August1st to 15thNight
79%
539
27%
1610
31%
536
80%
536
43%
857
August16th to endNight
74%
573
27%
1857
32%
573
77%
573
41%
970
September1st to 15thNight
67%
540
27%
1800
30%
540
69%
540
34%
988
September16th to endNight
63%
537
30%
1924
27%
537
71%
537
36%
1001
October1st to 15thNight
50%
660
29%
1980
21%
660
56%
660
37%
1117
October16th to endNight
41%
704
28%
2112
16%
704
51%
704
35%
1198
November1st to 15thNight
39%
700
31%
2118
16%
700
53%
700
34%
1203
November16th to endNight
29%
900
23%
2520
10%
900
40%
900
30%
1567
December1st to 15thNight
28%
900
19%
2520
7%
900
37%
900
25%
1677
December16th to endNight
27%
960
20%
2661
8%
960
36%
960
22%
1852

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%6%25%42445%7%43%
47876
Night
12%5%24423346%48%
47210
TransparencyDay
39%413%25%14%2
47576
Night
36%411%26%18%3
47015
SeeingDay
13%421%30%23%6%
5895
Night
15%7%28%32%15%1
15865

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
13%6%25%5%2334446%
1611
16th to endDay
14%8%36%423346%42%
1728
February1st to 15thDay
13%8%38%5%24345%39%
1575
16th to endDay
15%10%35%334346%39%
1560
March1st to 15thDay
15%10%36%5%43345%36%
1980
16th to endDay
22%9%35%433435%33%
2110
April1st to 15thDay
17%7%25%423445%42%
2122
16th to endDay
21%6%35%5%3345%6%33%
2183
May1st to 15thDay
19%6%25%5%3345%6%37%
2331
16th to endDay
13%6%36%5%35%45%8%37%
2508
June1st to 15thDay
8%425%5%35%46%8%44%
2520
16th to endDay
6%213425%46%11%51%
2520
July1st to 15thDay
8%3244445%7%9%44%
2375
16th to endDay
6%314436%5%7%9%45%
2466
August1st to 15thDay
6%4145%35%5%6%9%46%
2340
16th to endDay
8%3245%345%5%8%49%
2345
September1st to 15thDay
13%5%24423447%46%
2157
16th to endDay
8%42442435%7%52%
1860
October1st to 15thDay
14%5%1442233451%
1650
16th to endDay
13%5%25%422235%52%
1760
November1st to 15thDay
13%6%23222346%52%
1735
16th to endDay
19%6%23324237%44%
1440
December1st to 15thDay
15%9%45%425%445%39%
1440
16th to endDay
17%10%35%313237%39%
1560
January1st to 15thNight
12%5%245%23335%48%
2327
16th to endNight
10%8%35%423336%47%
2496
February1st to 15thNight
12%9%46%5%24446%40%
2278
16th to endNight
13%7%34313447%45%
1922
March1st to 15thNight
15%8%25%423346%43%
1980
16th to endNight
20%6%26%415%446%36%
2112
April1st to 15thNight
12%7%13312347%49%
1824
16th to endNight
16%6%36%5%23246%42%
1775
May1st to 15thNight
15%5%25%414446%43%
1619
16th to endNight
12%424425%35%8%45%
1602
June1st to 15thNight
5%3124245%7%11%52%
1440
16th to endNight
321232347%9%57%
1440
July1st to 15thNight
7%32432335%12%51%
1581
16th to endNight
422343335%9%56%
1702
August1st to 15thNight
43133335%5%8%57%
1620
16th to endNight
432433345%7%57%
1857
September1st to 15thNight
12%31332435%8%51%
1800
16th to endNight
7%2144235%6%6%54%
1924
October1st to 15thNight
12%315%323335%55%
1980
16th to endNight
11%414422435%56%
2112
November1st to 15thNight
11%5%12323325%56%
2118
16th to endNight
16%7%2432223450%
2520
December1st to 15thNight
18%9%2431335%5%42%
2520
16th to endNight
18%9%46%413335%39%
2661

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
40%311%26%17%
1612
16th to endDay
43%314%25%12%1
1728
February1st to 15thDay
47%315%23%9%
1576
16th to endDay
46%311%22%13%2
1560
March1st to 15thDay
49%310%21%12%2
1980
16th to endDay
54%313%18%8%1
2112
April1st to 15thDay
44%311%23%14%1
2122
16th to endDay
50%412%20%12%
2183
May1st to 15thDay
47%412%22%12%
2331
16th to endDay
44%6%14%21%11%
2512
June1st to 15thDay
35%6%14%26%15%1
2520
16th to endDay
25%6%17%33%15%2
2520
July1st to 15thDay
33%7%14%29%12%2
2236
16th to endDay
30%7%14%31%14%1
2311
August1st to 15thDay
33%5%17%26%16%
2326
16th to endDay
32%5%12%26%17%5%
2345
September1st to 15thDay
37%410%24%17%4
2157
16th to endDay
31%411%31%18%3
1860
October1st to 15thDay
37%29%24%21%4
1650
16th to endDay
36%38%28%17%5%
1760
November1st to 15thDay
33%311%26%20%5%
1735
16th to endDay
41%310%25%19%
1440
December1st to 15thDay
45%412%26%11%
1440
16th to endDay
47%314%22%10%2
1560
January1st to 15thNight
38%214%25%17%
2327
16th to endNight
39%313%26%15%1
2496
February1st to 15thNight
46%310%25%13%
2288
16th to endNight
38%312%25%17%2
1922
March1st to 15thNight
43%29%24%16%3
1980
16th to endNight
47%412%22%11%1
2112
April1st to 15thNight
35%410%25%20%3
1824
16th to endNight
43%310%25%15%1
1775
May1st to 15thNight
41%5%11%23%16%1
1620
16th to endNight
37%5%16%26%11%1
1604
June1st to 15thNight
24%5%16%31%19%1
1440
16th to endNight
20%5%15%31%23%3
1440
July1st to 15thNight
27%412%32%18%3
1491
16th to endNight
22%5%14%33%21%2
1594
August1st to 15thNight
23%6%12%35%19%2
1610
16th to endNight
26%412%24%25%6%
1857
September1st to 15thNight
31%410%26%21%6%
1800
16th to endNight
27%49%31%22%3
1924
October1st to 15thNight
31%29%25%22%7%
1980
16th to endNight
32%39%29%20%5%
2112
November1st to 15thNight
31%49%24%22%7%
2118
16th to endNight
38%27%28%19%2
2520
December1st to 15thNight
44%313%24%13%
2520
16th to endNight
48%311%20%12%2
2661

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%7%34%22%7%
90
16th to endDay
20%5%45%18%8%1
96
February1st to 15thDay
8%17%41%25%6%
90
16th to endDay
17%12%39%20%8%1
81
March1st to 15thDay
25%10%43%15%5%
90
16th to endDay
27%5%35%18%11%2
96
April1st to 15thDay
17%13%29%27%10%1
241
16th to endDay
24%433%23%12%1
293
May1st to 15thDay
20%6%30%28%11%2
468
16th to endDay
17%5%29%29%15%3
517
June1st to 15thDay
10%320%34%24%7%
495
16th to endDay
7%223%37%24%5%
495
July1st to 15thDay
11%113%34%30%8%
475
16th to endDay
6%18%30%41%13%
515
August1st to 15thDay
7%16%32%41%10%
493
16th to endDay
9%19%31%37%10%
385
September1st to 15thDay
12%27%29%36%10%
312
16th to endDay
5%17%31%30%14%
111
October1st to 15thDay
10%125%35%16%11%
90
16th to endDay
17%427%31%16%3
96
November1st to 15thDay
15%5%15%31%22%10%
90
16th to endDay
34%12%26%18%6%1
90
December1st to 15thDay
16%6%37%28%45%
90
16th to endDay
26%10%35%27%1
96
January1st to 15thNight
16%14%36%25%6%
900
16th to endNight
14%13%38%27%5%
960
February1st to 15thNight
17%12%38%27%3
880
16th to endNight
19%9%41%24%4
660
March1st to 15thNight
20%12%32%29%4
540
16th to endNight
21%8%34%29%6%
576
April1st to 15thNight
18%8%29%35%6%
539
16th to endNight
20%5%33%30%10%
540
May1st to 15thNight
15%6%27%35%14%
540
16th to endNight
14%325%34%18%2
563
June1st to 15thNight
6%119%41%29%1
540
16th to endNight
421%46%23%2
540
July1st to 15thNight
9%12%41%31%3
510
16th to endNight
5%7%37%45%3
564
August1st to 15thNight
6%5%41%40%5%
539
16th to endNight
5%10%38%39%5%
573
September1st to 15thNight
14%111%35%31%5%
540
16th to endNight
8%316%38%26%6%
537
October1st to 15thNight
14%326%32%19%3
660
16th to endNight
13%9%31%32%11%1
704
November1st to 15thNight
14%9%32%28%13%1
700
16th to endNight
20%10%37%23%7%
900
December1st to 15thNight
23%10%33%26%5%
900
16th to endNight
23%9%34%28%3
960
Page generated at 2017-09-24 08:15:57. Version ac04

Copyright 2017 A. Danko


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