Cranberry Corner
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cranberry Corner 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
29%
16479
12%
47805
6%
16432
34%
16432
18%
34713

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
16%
900
8%
2506
2%
895
22%
895
11%
2022
January16th to endNight
14%
960
7%
2688
1%
960
19%
960
11%
2189
February1st to 15thNight
19%
880
10%
2288
2%
876
24%
876
13%
1797
February16th to endNight
20%
666
10%
1928
5%
666
24%
666
13%
1511
March1st to 15thNight
28%
708
15%
2148
9%
708
33%
708
19%
1489
March16th to endNight
32%
576
15%
2007
12%
576
40%
576
18%
1365
April1st to 15thNight
26%
539
13%
1797
9%
539
33%
539
18%
1248
April16th to endNight
30%
540
14%
1707
9%
540
37%
540
18%
1194
May1st to 15thNight
29%
540
11%
1440
5%
540
32%
540
18%
1096
May16th to endNight
38%
563
12%
1498
5%
561
42%
561
24%
1031
June1st to 15thNight
41%
540
8%
1440
4%
540
44%
540
26%
983
June16th to endNight
42%
540
11%
1440
5%
540
45%
540
27%
967
July1st to 15thNight
52%
510
11%
1360
6%
510
53%
510
38%
835
July16th to endNight
53%
564
17%
1417
9%
531
56%
531
39%
853
August1st to 15thNight
54%
539
21%
1458
14%
536
58%
536
34%
914
August16th to endNight
45%
573
17%
1875
15%
573
50%
573
26%
1152
September1st to 15thNight
52%
540
20%
1800
18%
540
59%
540
29%
1055
September16th to endNight
37%
669
15%
1935
9%
669
44%
669
27%
1254
October1st to 15thNight
32%
720
17%
2160
11%
720
37%
720
22%
1458
October16th to endNight
26%
768
10%
2438
5%
768
32%
768
14%
1842
November1st to 15thNight
20%
799
13%
2510
6%
799
28%
799
15%
1814
November16th to endNight
19%
975
10%
2730
6%
975
23%
975
10%
2226
December1st to 15thNight
12%
910
4%
2547
1%
910
15%
910
8%
2150
December16th to endNight
13%
960
8%
2688
2%
960
18%
960
8%
2268

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%10%47%6%34446%30%
48652
Night
14%10%47%6%3445%6%31%
47972
Cloud CoverDay
28%8%36%5%33345%26%
48662
Night
26%9%36%5%23345%28%
47977
Cloud CoverDay
15%10%48%6%34446%29%
48660
Night
14%10%47%6%3445%6%31%
47977
TransparencyDay
53%5%12%18%8%
48337
Night
52%6%12%19%8%
47805
SeeingDay
20%11%32%21%10%3
6393
Night
19%11%32%25%9%
16479

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%13%8%13%10%6%5%44415%
1432
16th to endDay
11%15%8%12%8%36%6%7%5%13%
1536
February1st to 15thDay
9%13%5%11%8%46%6%5%7%21%
1572
16th to endDay
13%12%5%12%8%5%6%445%19%
1545
March1st to 15thDay
13%9%6%9%7%34346%29%
1811
16th to endDay
17%12%5%7%5%44436%29%
2217
April1st to 15thDay
17%11%5%7%6%24435%31%
2151
16th to endDay
19%11%46%6%3444430%
2252
May1st to 15thDay
20%11%36%5%24436%31%
2511
16th to endDay
15%8%36%5%3445%7%34%
2617
June1st to 15thDay
19%6%26%4345%47%34%
2520
16th to endDay
15%5%36%5%45%5%6%6%35%
2520
July1st to 15thDay
11%425%435%5%5%8%42%
2520
16th to endDay
11%4245%3445%8%43%
2655
August1st to 15thDay
12%6%345%35%5%5%7%40%
2490
16th to endDay
16%6%25%5%24448%38%
2327
September1st to 15thDay
13%7%25%433448%41%
2160
16th to endDay
21%8%36%423347%34%
2010
October1st to 15thDay
19%11%35%42345%5%33%
1800
16th to endDay
23%15%46%6%24345%23%
1785
November1st to 15thDay
16%16%47%6%24445%27%
1675
16th to endDay
16%15%8%11%8%35%45%5%15%
1560
December1st to 15thDay
15%15%8%13%11%46%43412%
1450
16th to endDay
16%20%9%17%8%35%3338%
1536
January1st to 15thNight
14%12%7%12%8%5%445%6%19%
2506
16th to endNight
11%14%8%11%7%5%5%5%5%6%16%
2688
February1st to 15thNight
10%11%7%10%8%46%5%6%6%22%
2285
16th to endNight
10%15%6%9%8%5%5%5%5%6%21%
1928
March1st to 15thNight
13%9%47%5%24445%38%
2135
16th to endNight
13%11%45%5%23445%37%
2007
April1st to 15thNight
21%9%36%422446%33%
1797
16th to endNight
20%8%36%5%2445%6%32%
1707
May1st to 15thNight
22%10%35%5%25%445%30%
1440
16th to endNight
13%6%25%5%25%36%8%39%
1496
June1st to 15thNight
13%7%245%3445%8%40%
1440
16th to endNight
12%5%245%3436%7%42%
1440
July1st to 15thNight
9%4134245%6%9%47%
1440
16th to endNight
8%32341436%8%52%
1513
August1st to 15thNight
9%4135%2445%7%50%
1467
16th to endNight
15%6%235%12346%47%
1875
September1st to 15thNight
11%424424446%49%
1800
16th to endNight
16%5%24434447%42%
1935
October1st to 15thNight
18%8%2342335%6%39%
2160
16th to endNight
20%12%36%5%3445%5%26%
2438
November1st to 15thNight
16%14%46%433346%30%
2510
16th to endNight
16%15%6%9%7%345%46%19%
2730
December1st to 15thNight
14%15%8%12%9%45%43416%
2547
16th to endNight
17%17%7%12%7%3444415%
2688

Percentage Cloud Cover SW (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
25%11%5%11%8%6%5%34314%
1432
16th to endDay
25%12%6%11%6%35%5%6%5%11%
1536
February1st to 15thDay
23%12%410%7%34445%18%
1572
16th to endDay
27%10%49%7%45%33417%
1545
March1st to 15thDay
26%8%47%7%33235%27%
1821
16th to endDay
31%9%36%5%3333424%
2217
April1st to 15thDay
30%9%36%5%2343425%
2151
16th to endDay
33%10%35%5%2333325%
2252
May1st to 15thDay
32%9%25%423335%26%
2511
16th to endDay
30%6%25%5%23345%29%
2617
June1st to 15thDay
33%5%14423435%28%
2520
16th to endDay
31%5%25%433445%28%
2520
July1st to 15thDay
26%414424446%36%
2520
16th to endDay
27%314423346%37%
2655
August1st to 15thDay
20%5%245%35%45%6%36%
2490
16th to endDay
23%5%15%423447%36%
2327
September1st to 15thDay
22%7%24423447%37%
2160
16th to endDay
26%7%26%423336%33%
2010
October1st to 15thDay
27%10%25%323345%31%
1800
16th to endDay
30%14%36%5%2333422%
1785
November1st to 15thDay
27%13%36%422345%25%
1675
16th to endDay
29%12%7%10%6%3434414%
1560
December1st to 15thDay
28%12%6%11%9%35%33411%
1450
16th to endDay
28%17%7%14%8%243327%
1536
January1st to 15thNight
25%9%411%7%5%4445%17%
2506
16th to endNight
25%13%5%10%6%45%45%6%13%
2688
February1st to 15thNight
24%10%5%8%7%3445%5%20%
2278
16th to endNight
23%13%48%7%5%4445%18%
1928
March1st to 15thNight
25%7%46%42333433%
2148
16th to endNight
27%9%35%412345%31%
2007
April1st to 15thNight
34%8%25%422345%28%
1797
16th to endNight
35%7%3441344426%
1707
May1st to 15thNight
34%8%25%42433425%
1439
16th to endNight
29%6%24423346%32%
1496
June1st to 15thNight
29%6%13422346%33%
1440
16th to endNight
28%5%245%2325%6%34%
1440
July1st to 15thNight
25%31332345%7%40%
1440
16th to endNight
25%313313246%45%
1513
August1st to 15thNight
18%3135%1445%6%46%
1467
16th to endNight
23%5%1342233444%
1875
September1st to 15thNight
19%324423446%44%
1800
16th to endNight
21%423433346%41%
1935
October1st to 15thNight
26%7%2342335%5%36%
2160
16th to endNight
27%11%25%5%34345%24%
2438
November1st to 15thNight
26%12%36%323345%28%
2510
16th to endNight
29%12%48%6%2343417%
2730
December1st to 15thNight
28%14%6%10%8%3433314%
2547
16th to endNight
29%15%6%11%6%2334413%
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%13%8%13%10%5%6%5%4414%
1432
16th to endDay
11%14%8%14%8%45%6%7%5%13%
1536
February1st to 15thDay
9%13%5%12%8%47%5%6%6%20%
1572
16th to endDay
13%12%7%12%10%45%5%45%19%
1545
March1st to 15thDay
12%11%6%10%7%34445%28%
1821
16th to endDay
16%12%5%9%7%24335%28%
2215
April1st to 15thDay
16%12%5%7%5%34445%30%
2151
16th to endDay
18%12%47%5%3444429%
2252
May1st to 15thDay
20%11%47%5%34436%29%
2511
16th to endDay
14%8%46%6%345%5%7%33%
2617
June1st to 15thDay
17%7%35%445%5%47%34%
2520
16th to endDay
14%6%25%6%46%5%5%7%34%
2520
July1st to 15thDay
10%5%345%345%6%9%41%
2520
16th to endDay
10%425%5%25%5%5%8%42%
2655
August1st to 15thDay
11%6%35%6%35%5%5%7%39%
2490
16th to endDay
15%7%345%25%5%5%7%38%
2327
September1st to 15thDay
13%8%26%5%24447%40%
2160
16th to endDay
20%8%36%423347%34%
2010
October1st to 15thDay
19%11%35%5%24447%32%
1800
16th to endDay
23%16%5%7%5%24335%22%
1785
November1st to 15thDay
16%16%48%6%34345%26%
1675
16th to endDay
15%16%8%11%9%5%4445%14%
1560
December1st to 15thDay
15%15%9%13%11%45%44312%
1450
16th to endDay
17%19%9%17%9%35%3237%
1536
January1st to 15thNight
14%11%6%12%8%5%5%5%5%5%17%
2506
16th to endNight
10%15%8%11%8%46%6%6%6%14%
2688
February1st to 15thNight
9%12%6%11%8%47%6%6%421%
2278
16th to endNight
11%14%7%8%9%45%6%5%6%20%
1928
March1st to 15thNight
13%10%47%5%34436%36%
2148
16th to endNight
13%10%5%6%5%23446%37%
2007
April1st to 15thNight
20%10%46%423345%33%
1797
16th to endNight
19%10%35%5%2445%6%32%
1707
May1st to 15thNight
21%10%35%6%34345%30%
1439
16th to endNight
12%7%25%5%345%5%8%38%
1496
June1st to 15thNight
13%7%25%5%3435%8%39%
1440
16th to endNight
12%6%26%43445%8%41%
1440
July1st to 15thNight
9%3234245%6%9%47%
1440
16th to endNight
8%32432337%7%52%
1513
August1st to 15thNight
8%5%2343447%6%49%
1467
16th to endNight
15%7%14413336%47%
1875
September1st to 15thNight
10%5%25%5%24447%48%
1800
16th to endNight
16%5%24434447%42%
1935
October1st to 15thNight
18%8%2342445%6%38%
2160
16th to endNight
19%14%36%6%3445%6%25%
2438
November1st to 15thNight
16%14%46%5%24346%30%
2510
16th to endNight
16%15%7%11%7%44436%18%
2730
December1st to 15thNight
13%16%8%12%10%45%44416%
2547
16th to endNight
16%18%8%13%7%24445%14%
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
69%48%11%5%
1433
16th to endDay
66%6%11%10%4
1536
February1st to 15thDay
60%6%13%14%5%
1573
16th to endDay
65%5%10%13%5%
1545
March1st to 15thDay
56%415%15%7%
1821
16th to endDay
56%5%13%17%5%
2217
April1st to 15thDay
54%412%17%9%
2151
16th to endDay
55%6%9%17%10%1
2252
May1st to 15thDay
54%6%11%19%7%
2511
16th to endDay
48%5%12%19%12%1
2621
June1st to 15thDay
47%6%12%23%9%
2520
16th to endDay
46%7%15%20%8%
2520
July1st to 15thDay
36%7%14%28%12%1
2371
16th to endDay
38%7%14%23%14%1
2488
August1st to 15thDay
41%6%15%24%10%1
2475
16th to endDay
43%7%16%20%12%
2327
September1st to 15thDay
41%5%16%26%9%
2160
16th to endDay
50%5%13%22%7%
2010
October1st to 15thDay
51%5%12%21%8%
1800
16th to endDay
63%5%10%15%5%
1785
November1st to 15thDay
58%311%18%7%
1675
16th to endDay
70%5%11%8%3
1560
December1st to 15thDay
74%49%9%2
1450
16th to endDay
81%45%6%1
1536
January1st to 15thNight
64%5%10%15%3
2506
16th to endNight
64%6%11%13%3
2688
February1st to 15thNight
58%6%11%16%6%
2288
16th to endNight
61%5%11%15%5%
1928
March1st to 15thNight
47%6%12%20%11%
2148
16th to endNight
47%6%13%19%10%
2007
April1st to 15thNight
51%410%20%11%1
1797
16th to endNight
51%411%19%11%1
1707
May1st to 15thNight
55%5%12%17%7%1
1440
16th to endNight
43%7%14%21%12%1
1498
June1st to 15thNight
41%7%14%24%11%
1440
16th to endNight
39%8%15%23%11%1
1440
July1st to 15thNight
29%8%14%33%13%1
1360
16th to endNight
28%7%17%29%13%2
1417
August1st to 15thNight
32%8%12%30%14%1
1458
16th to endNight
38%6%13%24%13%3
1875
September1st to 15thNight
33%6%13%33%12%
1800
16th to endNight
40%5%17%28%8%
1935
October1st to 15thNight
44%6%12%25%10%
2160
16th to endNight
57%5%13%15%6%
2438
November1st to 15thNight
54%413%18%8%
2510
16th to endNight
65%5%12%10%41
2730
December1st to 15thNight
70%5%11%9%2
2547
16th to endNight
70%5%10%10%3
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
23%10%37%24%4
90
16th to endDay
27%13%34%25%
96
February1st to 15thDay
17%24%45%10%11
90
16th to endDay
28%14%44%11%1
81
March1st to 15thDay
18%18%34%20%7%
90
16th to endDay
26%10%29%21%7%4
201
April1st to 15thDay
22%11%31%24%8%1
270
16th to endDay
24%15%29%21%6%2
288
May1st to 15thDay
25%16%35%15%5%2
468
16th to endDay
21%14%33%17%8%3
517
June1st to 15thDay
20%11%32%23%10%2
495
16th to endDay
16%13%35%17%13%2
495
July1st to 15thDay
13%7%32%26%12%7%
475
16th to endDay
12%6%34%24%14%7%
515
August1st to 15thDay
15%6%24%30%17%4
493
16th to endDay
20%6%24%25%17%5%
367
September1st to 15thDay
15%6%24%27%18%6%
315
16th to endDay
22%8%30%27%9%3
308
October1st to 15thDay
24%14%30%14%14%1
135
16th to endDay
35%16%29%15%2
144
November1st to 15thDay
19%14%42%17%6%
135
16th to endDay
28%17%34%16%3
135
December1st to 15thDay
22%7%48%18%3
94
16th to endDay
30%26%30%13%
96
January1st to 15thNight
18%14%40%19%6%
900
16th to endNight
18%14%43%19%4
960
February1st to 15thNight
17%14%38%23%5%
880
16th to endNight
18%12%40%22%6%
666
March1st to 15thNight
18%12%34%26%7%
708
16th to endNight
17%12%32%26%9%1
576
April1st to 15thNight
25%9%33%25%6%
539
16th to endNight
25%10%30%26%7%
540
May1st to 15thNight
24%14%28%26%5%
540
16th to endNight
15%10%30%30%11%1
563
June1st to 15thNight
19%7%27%33%11%
540
16th to endNight
15%6%30%31%15%
540
July1st to 15thNight
11%329%35%19%1
510
16th to endNight
10%228%37%19%1
564
August1st to 15thNight
12%225%34%23%1
539
16th to endNight
18%425%30%18%2
573
September1st to 15thNight
13%6%22%32%19%4
540
16th to endNight
18%8%31%27%13%1
669
October1st to 15thNight
23%10%31%22%11%
720
16th to endNight
28%12%26%23%8%
768
November1st to 15thNight
23%15%35%19%5%1
799
16th to endNight
24%18%32%19%4
975
December1st to 15thNight
20%21%35%19%3
910
16th to endNight
23%15%36%19%4
960
Page generated at 2017-12-03 10:16:45. Version ac04

Copyright 2017 A. Danko


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