Sachs Harbour
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sachs Harbour clear sky chart from 2005-11-06 to 2024-01-16.

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
0%
5130
0%
61586
0%
4472
0%
4472
14%
57059

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 10thNight
0%
281
0%
3355
0%
235
0%
235
18%
3087
January11th to 20thNight
0%
251
0%
3221
0%
201
0%
201
20%
2853
January21st to endNight
0%
138
0%
2924
0%
105
0%
105
20%
2970
February1st to 10thNight
0%
152
0%
2428
0%
129
0%
129
18%
2338
February11th to 20thNight
0%
168
0%
1997
0%
134
0%
134
22%
1958
February21st to endNight
0%
108
0%
1537
0%
82
0%
82
20%
1508
March1st to 10thNight
0%
101
0%
1538
0%
75
0%
75
26%
1473
March11th to 20thNight
0%
102
0%
1388
0%
81
0%
81
24%
1431
March21st to endNight
0%
89
0%
1354
0%
73
0%
73
26%
1352
April1st to 10thNight
0%
54
0%
1011
0%
41
0%
41
24%
943
April11th to 20thNight
0%
57
0%
803
0%
48
0%
48
22%
769
April21st to endNight
0%
67
0%
556
0%
59
0%
59
26%
595
May1st to 10thNight
0%
9
0%
246
0%
6
0%
6
14%
230
May11th to 20thNight00000
May21st to endNight00000
June1st to 10thNight00000
June11th to 20thNight00000
June21st to endNight00000
July1st to 10thNight00000
July11th to 20thNight00000
July21st to endNight00000
August1st to 10thNight
0%
24
0%
259
0%
24
0%
24
5%
223
August11th to 20thNight
0%
134
0%
699
0%
132
0%
132
11%
633
August21st to endNight
0%
148
0%
1199
0%
148
0%
148
8%
1054
September1st to 10thNight
0%
159
0%
1342
0%
156
0%
156
8%
1204
September11th to 20thNight
0%
259
0%
1600
0%
248
0%
248
10%
1468
September21st to endNight
0%
323
0%
1992
0%
318
0%
318
6%
1843
October1st to 10thNight
0%
246
0%
2152
0%
233
0%
233
8%
1943
October11th to 20thNight
0%
284
0%
2388
0%
262
0%
262
10%
2114
October21st to endNight
0%
379
0%
3044
0%
364
0%
364
9%
2759
November1st to 10thNight
0%
257
0%
3046
0%
211
0%
211
12%
2656
November11th to 20thNight
0%
303
0%
3918
0%
249
0%
249
7%
3639
November21st to endNight
0%
255
0%
3907
0%
233
0%
233
9%
3554
December1st to 10thNight
0%
298
0%
3641
0%
251
0%
251
14%
3244
December11th to 20thNight
0%
237
0%
3728
0%
189
0%
189
15%
3392
December21st to endNight
0%
247
0%
6313
0%
185
0%
185
9%
5826

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
TransparencyDay
54%7%18%17%3
76350
Night
54%7%16%18%4
79169
SeeingDay
14%313%27%30%14%
18551
Night
8%213%29%32%16%
21933

By Month

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
January21st to endDay
46%217%30%32
63
February1st to 10thDay
47%6%22%20%5%
596
11th to 20thDay
44%10%15%26%5%
968
21st to endDay
46%8%13%27%5%
1036
March1st to 10thDay
39%7%21%23%10%
1584
11th to 20thDay
45%8%16%25%6%1
1871
21st to endDay
44%7%17%23%8%
2380
April1st to 10thDay
41%6%20%26%7%
2467
11th to 20thDay
50%7%16%21%6%
2741
21st to endDay
48%6%16%24%6%
3145
May1st to 10thDay
59%5%14%17%4
3625
11th to 20thDay
52%7%18%19%4
4253
21st to endDay
50%5%15%22%7%
4664
June1st to 10thDay
48%6%18%24%4
4320
11th to 20thDay
49%10%20%18%2
4320
21st to endDay
44%9%25%21%1
4320
July1st to 10thDay
43%8%21%25%3
4201
11th to 20thDay
56%9%21%13%1
4185
21st to endDay
58%8%22%12%
4449
August1st to 10thDay
65%8%18%8%1
3701
11th to 20thDay
67%9%17%6%1
3145
21st to endDay
70%8%17%5%
3111
September1st to 10thDay
74%415%6%
2501
11th to 20thDay
66%7%21%6%
2226
21st to endDay
75%7%15%4
1904
October1st to 10thDay
68%8%16%8%1
1626
11th to 20thDay
65%9%18%9%1
1316
21st to endDay
67%6%21%7%
1050
November1st to 10thDay
62%6%18%14%
549
11th to 20thDay
79%12%9%
33
January1st to 10thNight
49%7%18%22%4
4545
11th to 20thNight
45%6%21%21%6%
4453
21st to endNight
46%6%12%26%10%
4553
February1st to 10thNight
48%9%16%21%7%
3362
11th to 20thNight
45%7%16%25%6%
2905
21st to endNight
47%6%16%26%5%
2220
March1st to 10thNight
40%6%19%25%10%
2373
11th to 20thNight
45%7%15%26%6%1
2087
21st to endNight
45%6%18%24%7%1
1976
April1st to 10thNight
40%7%20%26%6%
1494
11th to 20thNight
44%7%18%25%6%
1166
21st to endNight
47%7%15%24%8%
813
May1st to 10thNight
53%414%23%5%
342
August1st to 10thNight
67%9%18%5%1
276
11th to 20thNight
66%8%18%6%1
753
21st to endNight
68%10%19%4
1246
September1st to 10thNight
72%316%8%
1458
11th to 20thNight
68%7%17%7%
1732
21st to endNight
77%7%13%3
2056
October1st to 10thNight
64%12%16%8%
2334
11th to 20thNight
64%7%19%9%
2626
21st to endNight
70%5%17%8%
3306
November1st to 10thNight
59%7%21%12%1
3525
11th to 20thNight
66%10%12%10%2
4413
21st to endNight
63%8%15%11%3
4560
December1st to 10thNight
50%10%19%16%4
4560
11th to 20thNight
43%8%16%29%6%
5675
21st to endNight
56%7%13%20%4
8360

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
February1st to 10thDay
137%24%39%26%
90
11th to 20thDay
5%18%27%38%22%
160
21st to endDay
2210%27%32%27%
132
March1st to 10thDay
2114%24%37%21%
327
11th to 20thDay
4314%27%35%17%
398
21st to endDay
5%110%32%32%19%
462
April1st to 10thDay
4111%21%35%28%
456
11th to 20thDay
3310%29%37%18%
662
21st to endDay
4211%29%33%22%
780
May1st to 10thDay
9%313%24%34%17%
868
11th to 20thDay
6%412%28%33%16%
1156
21st to endDay
6%210%26%37%19%
1263
June1st to 10thDay
9%213%26%32%18%
1170
11th to 20thDay
12%317%29%30%10%
1170
21st to endDay
14%413%30%29%11%
1170
July1st to 10thDay
13%211%26%33%14%
1146
11th to 20thDay
17%413%26%29%12%
1140
21st to endDay
21%411%26%28%9%
1275
August1st to 10thDay
27%5%13%25%21%9%
949
11th to 20thDay
27%413%26%22%8%
793
21st to endDay
25%312%23%26%10%
783
September1st to 10thDay
29%312%21%21%13%
497
11th to 20thDay
24%5%16%27%22%7%
450
21st to endDay
24%8%16%27%17%8%
450
October1st to 10thDay
16%417%29%24%10%
339
11th to 20thDay
14%317%24%25%17%
180
21st to endDay
12%7%20%25%27%10%
198
November1st to 10thDay
11%213%32%25%16%
87
January1st to 10thNight
5%117%32%29%16%
1220
11th to 20thNight
4215%31%33%14%
1185
21st to endNight
218%32%36%21%
1224
February1st to 10thNight
2211%30%33%21%
988
11th to 20thNight
5%212%28%36%18%
914
21st to endNight
3211%29%33%21%
658
March1st to 10thNight
3110%31%37%18%
730
11th to 20thNight
3210%25%37%23%
720
21st to endNight
319%31%36%21%
707
April1st to 10thNight
228%30%37%21%
450
11th to 20thNight
6%19%32%36%16%
355
21st to endNight
6%112%31%36%14%
349
May1st to 10thNight
6%7%29%35%22%
68
August1st to 10thNight
28%210%20%30%11%
61
11th to 20thNight
29%5%11%23%27%5%
299
21st to endNight
24%410%24%28%11%
396
September1st to 10thNight
26%39%27%28%7%
424
11th to 20thNight
21%5%14%29%23%8%
648
21st to endNight
24%5%16%26%22%7%
720
October1st to 10thNight
17%313%31%27%8%
720
11th to 20thNight
16%5%16%29%24%10%
786
21st to endNight
17%414%27%28%10%
1089
November1st to 10thNight
8%215%30%33%12%
1015
11th to 20thNight
6%317%29%31%15%
1205
21st to endNight
7%212%27%34%19%
1220
December1st to 10thNight
5%317%28%29%19%
1220
11th to 20thNight
4412%31%30%20%
1220
21st to endNight
3313%33%35%13%
1342
Page generated at 2024-01-13 07:37:52. Version ac07

Copyright 2024 Attilla Danko


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