Guysborough
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Guysborough clear sky chart from 2005-11-05 to 2017-12-01.

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
19%
15579
11%
47808
4%
15535
26%
15535
13%
35829

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
8%
749
9%
2506
1%
746
18%
746
8%
1921
January16th to endNight
9%
789
11%
2619
1%
789
21%
789
9%
1966
February1st to 15thNight
10%
704
9%
2286
1%
701
19%
701
9%
1754
February16th to endNight
14%
631
9%
1970
2%
631
21%
631
9%
1533
March1st to 15thNight
16%
717
12%
2076
4%
717
23%
717
11%
1632
March16th to endNight
15%
708
13%
2052
4%
708
26%
708
13%
1551
April1st to 15thNight
15%
539
12%
1796
4%
539
24%
539
12%
1328
April16th to endNight
20%
540
13%
1708
6%
540
28%
540
15%
1242
May1st to 15thNight
22%
540
11%
1440
5%
540
27%
540
15%
1120
May16th to endNight
21%
561
11%
1496
4%
560
26%
560
17%
1133
June1st to 15thNight
20%
540
5%
1440
1%
540
23%
540
13%
1154
June16th to endNight
22%
540
6%
1440
2%
540
24%
540
17%
1106
July1st to 15thNight
29%
510
7%
1360
3%
510
32%
510
23%
972
July16th to endNight
30%
565
9%
1419
5%
532
31%
532
17%
1084
August1st to 15thNight
33%
539
10%
1539
7%
535
35%
535
18%
1136
August16th to endNight
37%
573
15%
1848
9%
573
44%
573
22%
1217
September1st to 15thNight
29%
540
14%
1800
9%
540
37%
540
19%
1203
September16th to endNight
26%
603
19%
1967
10%
603
36%
603
19%
1296
October1st to 15thNight
23%
720
15%
2160
6%
720
32%
720
20%
1498
October16th to endNight
17%
787
13%
2379
4%
787
23%
787
13%
1758
November1st to 15thNight
17%
805
11%
2558
3%
805
24%
805
12%
1922
November16th to endNight
16%
825
12%
2730
3%
825
26%
825
9%
2087
December1st to 15thNight
11%
754
9%
2531
1%
754
22%
754
7%
2001
December16th to endNight
7%
800
6%
2688
1%
800
14%
800
5%
2215

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
21%10%47%6%3445%6%26%
48629
Night
20%9%46%5%3445%6%27%
47980
TransparencyDay
57%6%11%16%7%
48319
Night
56%6%11%17%7%
47808
SeeingDay
27%19%30%16%5%1
7940
Night
26%17%31%18%5%
15583

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
16%12%5%7%6%36%47%7%21%
1432
16th to endDay
18%11%5%8%6%3446%7%23%
1603
February1st to 15thDay
17%10%49%9%45%45%6%23%
1575
16th to endDay
12%13%7%8%8%35%446%23%
1503
March1st to 15thDay
16%13%5%8%6%45%45%6%23%
1872
16th to endDay
17%13%8%7%7%33335%26%
2172
April1st to 15thDay
23%12%46%5%2434426%
2153
16th to endDay
25%10%25%5%24336%29%
2249
May1st to 15thDay
28%10%46%423335%25%
2512
16th to endDay
21%10%37%5%3435%6%26%
2618
June1st to 15thDay
29%9%35%5%345%46%21%
2520
16th to endDay
25%9%37%5%3445%6%24%
2520
July1st to 15thDay
18%5%36%5%45%5%5%7%31%
2520
16th to endDay
22%9%36%5%35%5%5%7%23%
2653
August1st to 15thDay
22%8%36%5%3445%7%28%
2409
16th to endDay
16%6%35%5%35%5%6%8%34%
2354
September1st to 15thDay
20%7%36%5%34345%33%
2160
16th to endDay
19%6%25%5%345%48%34%
1992
October1st to 15thDay
20%7%36%5%35%5%47%30%
1800
16th to endDay
22%10%47%6%345%5%6%23%
1844
November1st to 15thDay
26%10%36%5%33446%25%
1629
16th to endDay
17%13%36%6%35%45%7%24%
1560
December1st to 15thDay
22%13%48%5%46%5%5%6%15%
1443
16th to endDay
22%11%7%10%7%45%45%5%16%
1536
January1st to 15thNight
17%11%5%7%6%35%5%5%6%23%
2506
16th to endNight
17%11%5%8%6%35%45%6%24%
2619
February1st to 15thNight
18%11%48%6%45%445%24%
2285
16th to endNight
13%11%8%8%5%36%5%5%6%23%
1970
March1st to 15thNight
18%10%5%9%6%45%45%5%23%
2064
16th to endNight
20%11%5%6%5%33435%29%
2052
April1st to 15thNight
23%11%36%425%436%27%
1796
16th to endNight
27%7%25%433445%29%
1708
May1st to 15thNight
31%8%35%423336%26%
1440
16th to endNight
19%8%45%7%35%45%8%27%
1494
June1st to 15thNight
28%9%37%434446%23%
1440
16th to endNight
24%9%36%5%2435%7%26%
1440
July1st to 15thNight
16%7%26%435%47%9%30%
1440
16th to endNight
19%8%46%6%45%5%5%8%24%
1515
August1st to 15thNight
21%6%36%6%44446%31%
1550
16th to endNight
15%5%25%6%25%45%8%36%
1848
September1st to 15thNight
17%6%34435%447%37%
1800
16th to endNight
18%7%35%433346%39%
1967
October1st to 15thNight
21%6%25%5%24447%34%
2160
16th to endNight
23%8%35%5%3445%6%29%
2379
November1st to 15thNight
21%11%36%5%3445%6%25%
2558
16th to endNight
19%13%36%5%3445%6%26%
2730
December1st to 15thNight
23%11%47%6%3445%7%21%
2531
16th to endNight
24%11%6%8%5%35%5%46%17%
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
59%7%10%14%6%
1433
16th to endDay
58%7%10%14%9%
1603
February1st to 15thDay
62%410%13%8%
1578
16th to endDay
61%5%9%13%8%1
1503
March1st to 15thDay
60%5%8%15%8%
1883
16th to endDay
61%49%16%6%1
2172
April1st to 15thDay
59%5%7%13%11%2
2153
16th to endDay
56%411%15%10%
2249
May1st to 15thDay
62%49%15%6%
2512
16th to endDay
58%6%10%17%6%
2622
June1st to 15thDay
63%6%11%12%4
2520
16th to endDay
59%7%11%14%6%
2520
July1st to 15thDay
49%7%15%19%7%
2372
16th to endDay
58%7%13%14%5%
2486
August1st to 15thDay
55%6%13%18%6%
2395
16th to endDay
45%7%17%22%7%
2354
September1st to 15thDay
51%5%11%21%9%
2160
16th to endDay
47%5%10%24%10%
1992
October1st to 15thDay
54%6%10%20%8%
1800
16th to endDay
59%6%12%15%6%
1844
November1st to 15thDay
60%5%12%15%6%
1629
16th to endDay
59%8%12%14%5%
1560
December1st to 15thDay
65%9%9%13%2
1443
16th to endDay
69%7%6%10%4
1536
January1st to 15thNight
57%9%11%14%6%
2506
16th to endNight
58%6%10%17%6%
2619
February1st to 15thNight
61%410%14%8%
2286
16th to endNight
59%7%10%15%5%
1970
March1st to 15thNight
61%5%8%16%7%
2076
16th to endNight
57%49%18%9%1
2052
April1st to 15thNight
57%5%9%15%9%1
1796
16th to endNight
55%410%15%12%1
1708
May1st to 15thNight
60%39%18%6%
1440
16th to endNight
54%6%11%20%7%
1496
June1st to 15thNight
62%5%10%15%5%
1440
16th to endNight
56%6%11%16%8%
1440
July1st to 15thNight
47%7%17%18%9%
1360
16th to endNight
56%5%15%16%4
1419
August1st to 15thNight
53%5%15%19%5%
1539
16th to endNight
43%7%17%23%8%
1848
September1st to 15thNight
46%5%13%24%9%
1800
16th to endNight
45%5%11%25%11%
1967
October1st to 15thNight
47%5%12%23%10%
2160
16th to endNight
55%5%11%19%7%
2379
November1st to 15thNight
56%7%13%15%6%
2558
16th to endNight
58%7%11%15%7%
2730
December1st to 15thNight
62%7%10%14%4
2531
16th to endNight
66%7%10%10%4
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
19%36%30%12%
240
16th to endDay
26%28%30%11%2
256
February1st to 15thDay
22%31%29%14%1
236
16th to endDay
21%27%29%17%3
212
March1st to 15thDay
22%32%29%9%5%
254
16th to endDay
27%27%27%12%41
288
April1st to 15thDay
30%28%28%9%1
270
16th to endDay
25%22%28%18%5%
281
May1st to 15thDay
37%16%22%15%5%2
468
16th to endDay
28%15%33%16%41
519
June1st to 15thDay
36%15%28%13%4
495
16th to endDay
31%10%34%18%4
495
July1st to 15thDay
22%8%36%25%7%1
475
16th to endDay
29%8%27%23%10%
514
August1st to 15thDay
25%8%29%26%9%1
382
16th to endDay
20%11%31%24%10%1
332
September1st to 15thDay
25%13%36%18%6%
315
16th to endDay
23%14%29%23%6%1
288
October1st to 15thDay
21%20%31%17%7%2
270
16th to endDay
24%28%29%9%6%2
288
November1st to 15thDay
28%18%30%14%5%2
280
16th to endDay
26%27%29%11%5%
285
December1st to 15thDay
32%26%26%11%2
241
16th to endDay
25%32%28%10%21
256
January1st to 15thNight
22%27%35%13%1
750
16th to endNight
25%29%31%11%2
789
February1st to 15thNight
27%22%34%12%2
704
16th to endNight
20%27%32%15%4
631
March1st to 15thNight
24%22%31%17%4
720
16th to endNight
26%21%30%16%4
708
April1st to 15thNight
28%18%33%14%4
539
16th to endNight
31%15%29%20%3
540
May1st to 15thNight
37%12%25%18%6%1
540
16th to endNight
24%14%35%19%5%1
561
June1st to 15thNight
33%11%30%23%1
540
16th to endNight
30%7%36%21%5%
540
July1st to 15thNight
22%438%27%6%
510
16th to endNight
23%6%33%27%8%
565
August1st to 15thNight
26%5%28%28%11%
539
16th to endNight
17%7%31%33%9%
573
September1st to 15thNight
20%9%35%23%9%1
540
16th to endNight
24%10%32%24%7%
603
October1st to 15thNight
24%14%31%19%8%
720
16th to endNight
27%21%30%15%5%
787
November1st to 15thNight
28%17%32%14%5%1
805
16th to endNight
27%23%28%14%5%
825
December1st to 15thNight
30%27%26%10%4
754
16th to endNight
30%28%26%10%31
800
Page generated at 2017-12-02 10:14:25. Version ac04

Copyright 2017 A. Danko


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