White Rock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the White Rock clear sky chart from 2005-11-06 to 2024-02-05.

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
41%
22641
6%
80675
5%
22517
42%
22517
7%
67298

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
20%
839
2%
4713
2%
816
21%
816
1%
4286
January11th to 20thNight
29%
839
13%
4611
4%
814
32%
814
3%
3471
January21st to endNight
27%
836
3%
4827
4%
814
30%
814
3%
4415
February1st to 10thNight
25%
738
3%
2397
1%
738
27%
738
5%
2127
February11th to 20thNight
30%
700
6%
2274
5%
700
31%
700
6%
1952
February21st to endNight
29%
592
6%
1901
4%
592
33%
592
5%
1664
March1st to 10thNight
32%
720
5%
2106
4%
720
34%
720
7%
1846
March11th to 20thNight
31%
720
6%
1979
3%
720
32%
720
6%
1766
March21st to endNight
31%
792
3%
2117
2%
792
32%
792
6%
1903
April1st to 10thNight
35%
720
3%
1800
1%
720
36%
720
8%
1594
April11th to 20thNight
39%
633
10%
1701
6%
633
41%
633
10%
1436
April21st to endNight
39%
485
5%
1565
4%
485
40%
485
7%
1345
May1st to 10thNight
55%
360
9%
1440
13%
360
56%
360
9%
1123
May11th to 20thNight
61%
354
8%
1416
14%
354
62%
354
10%
1062
May21st to endNight
58%
389
4%
1526
6%
388
59%
388
8%
1237
June1st to 10thNight
52%
360
2%
1260
2%
360
53%
360
8%
1037
June11th to 20thNight
46%
360
2%
1260
1%
360
47%
360
8%
1044
June21st to endNight
62%
360
5%
1260
3%
360
63%
360
13%
933
July1st to 10thNight
69%
350
7%
1225
7%
350
69%
350
17%
863
July11th to 20thNight
72%
348
11%
1218
15%
348
73%
348
19%
820
July21st to endNight
82%
394
14%
1460
22%
372
85%
372
21%
907
August1st to 10thNight
77%
371
11%
1437
16%
369
77%
369
16%
959
August11th to 20thNight
80%
534
17%
1602
17%
534
80%
534
24%
1071
August21st to endNight
66%
659
14%
1847
12%
659
66%
659
17%
1378
September1st to 10thNight
73%
720
15%
1800
10%
720
73%
720
26%
1292
September11th to 20thNight
54%
720
14%
1800
8%
720
56%
720
18%
1408
September21st to endNight
52%
720
12%
2061
10%
720
53%
720
13%
1634
October1st to 10thNight
51%
720
8%
2160
8%
720
53%
720
13%
1693
October11th to 20thNight
40%
720
6%
2160
5%
720
42%
720
10%
1782
October21st to endNight
35%
792
6%
2510
4%
792
37%
792
7%
2116
November1st to 10thNight
28%
740
4%
2590
3%
740
29%
740
4%
2343
November11th to 20thNight
28%
760
4%
2660
4%
760
28%
760
4%
2356
November21st to endNight
26%
760
2%
2660
1%
760
28%
760
3%
2391
December1st to 10thNight
35%
760
4%
2660
3%
760
37%
760
5%
2327
December11th to 20thNight
19%
843
1%
3501
0%
842
20%
842
2%
3207
December21st to endNight
18%
933
3%
5171
2%
905
21%
905
2%
4510

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
23%8%36%5%34446%33%
77825
Night
28%9%36%5%34446%29%
80979
TransparencyDay
36%38%10%11%41
77536
Night
40%36%8%10%41
80848
SeeingDay
25%6%18%25%20%6%
14228
Night
32%5%14%24%21%5%
22663

By Month

Percentage Cloud Cover NW (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 10thDay
40%12%38%6%34445%11%
2219
11th to 20thDay
28%13%47%5%33336%23%
2209
21st to endDay
51%12%36%5%3323310%
2827
February1st to 10thDay
34%12%37%6%3435%5%18%
1657
11th to 20thDay
30%9%37%6%35%5%46%22%
1575
21st to endDay
26%12%46%6%25%5%46%24%
1354
March1st to 10thDay
28%13%37%6%44445%22%
1853
11th to 20thDay
31%10%47%6%34335%23%
1980
21st to endDay
27%11%47%6%345%46%24%
2238
April1st to 10thDay
25%10%36%6%35%5%5%7%24%
2160
11th to 20thDay
21%9%46%7%46%46%6%28%
2206
21st to endDay
21%9%46%6%345%6%6%30%
2394
May1st to 10thDay
16%6%36%6%35%5%47%39%
2520
11th to 20thDay
16%7%26%5%25%5%6%8%36%
2477
21st to endDay
18%7%37%5%345%5%6%36%
2746
June1st to 10thDay
21%6%35%5%45%45%7%34%
2700
11th to 20thDay
21%6%37%6%345%5%7%33%
2700
21st to endDay
13%6%35%6%36%5%6%7%43%
2700
July1st to 10thDay
12%42442435%7%53%
2700
11th to 20thDay
10%424434446%56%
2700
21st to endDay
8%212223346%67%
2769
August1st to 10thDay
9%5%24323446%60%
2491
11th to 20thDay
8%5%23323447%59%
2298
21st to endDay
12%5%24435%5%5%7%49%
2508
September1st to 10thDay
12%6%35%43445%7%49%
2160
11th to 20thDay
16%8%36%5%34447%41%
2160
21st to endDay
22%7%25%5%2445%6%37%
1896
October1st to 10thDay
22%8%36%5%3445%8%32%
1800
11th to 20thDay
28%9%37%6%25%5%6%8%23%
1800
21st to endDay
32%9%36%6%34346%24%
1842
November1st to 10thDay
37%8%35%6%3445%5%19%
1488
11th to 20thDay
35%9%37%5%32445%23%
1520
21st to endDay
35%11%47%435%445%18%
1520
December1st to 10thDay
32%13%45%5%3443324%
1520
11th to 20thDay
35%13%47%5%46%445%14%
1696
21st to endDay
33%13%5%9%7%45%44411%
2442
January1st to 10thNight
37%13%48%6%3444412%
4726
11th to 20thNight
32%9%25%5%2445%7%25%
4686
21st to endNight
49%11%46%42323412%
4827
February1st to 10thNight
35%11%36%5%3435%5%20%
2397
11th to 20thNight
29%12%37%5%34445%25%
2272
21st to endNight
29%10%36%5%34446%26%
1901
March1st to 10thNight
29%10%35%6%35%445%25%
2106
11th to 20thNight
33%9%36%6%34445%23%
1979
21st to endNight
31%12%47%6%34445%19%
2117
April1st to 10thNight
28%10%46%5%35%5%5%6%24%
1800
11th to 20thNight
23%9%47%5%35%5%46%29%
1701
21st to endNight
25%8%47%7%445%5%6%26%
1565
May1st to 10thNight
17%6%36%445%45%6%41%
1440
11th to 20thNight
14%5%36%5%35%6%8%8%37%
1416
21st to endNight
17%7%36%6%45%45%7%37%
1526
June1st to 10thNight
21%6%38%5%35%46%6%33%
1260
11th to 20thNight
17%9%47%6%35%6%6%6%30%
1260
21st to endNight
13%5%25%5%3445%8%45%
1260
July1st to 10thNight
10%5%25%5%2345%5%55%
1260
11th to 20thNight
7%5%25%423335%61%
1260
21st to endNight
5%312323346%69%
1546
August1st to 10thNight
8%323223445%64%
1445
11th to 20thNight
6%313423349%63%
1602
21st to endNight
8%425%6%3448%8%47%
1847
September1st to 10thNight
9%32343345%8%57%
1800
11th to 20thNight
19%5%26%5%3335%5%43%
1800
21st to endNight
19%5%36%6%23447%40%
2061
October1st to 10thNight
20%6%25%5%35%5%5%5%39%
2160
11th to 20thNight
29%6%45%435%45%6%30%
2160
21st to endNight
31%7%26%5%23447%29%
2510
November1st to 10thNight
38%8%36%5%45%445%18%
2590
11th to 20thNight
36%9%35%5%34346%22%
2660
21st to endNight
35%10%47%5%35%44419%
2660
December1st to 10thNight
32%8%45%435%5%5%6%24%
2660
11th to 20thNight
42%13%47%5%2343412%
3505
21st to endNight
35%14%47%5%3433416%
5214

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 10thDay
61%29%5%5%
2219
11th to 20thDay
49%26%9%9%5%3
2230
21st to endDay
67%24%431
2827
February1st to 10thDay
46%39%8%5%2
1657
11th to 20thDay
43%39%5%8%41
1584
21st to endDay
43%39%8%7%3
1354
March1st to 10thDay
43%39%7%7%31
1853
11th to 20thDay
44%38%7%8%2
1980
21st to endDay
43%39%8%8%2
2238
April1st to 10thDay
41%39%12%5%2
2160
11th to 20thDay
36%38%8%9%7%1
2206
21st to endDay
37%40%10%8%41
2394
May1st to 10thDay
33%40%10%13%4
2520
11th to 20thDay
30%40%12%13%5%1
2480
21st to endDay
36%40%11%11%2
2747
June1st to 10thDay
35%39%11%10%32
2700
11th to 20thDay
35%40%15%9%1
2700
21st to endDay
28%39%14%14%5%1
2700
July1st to 10thDay
19%40%14%17%7%2
2626
11th to 20thDay
19%39%14%21%7%1
2619
21st to endDay
13%39%13%22%10%3
2615
August1st to 10thDay
20%40%13%21%5%1
2474
11th to 20thDay
18%37%15%18%10%2
2298
21st to endDay
23%40%13%18%5%1
2508
September1st to 10thDay
19%39%13%17%9%4
2160
11th to 20thDay
25%40%10%14%9%1
2160
21st to endDay
33%40%8%12%6%1
1896
October1st to 10thDay
33%40%11%10%6%
1800
11th to 20thDay
38%41%10%8%21
1800
21st to endDay
40%40%8%7%5%
1842
November1st to 10thDay
44%43%5%5%31
1488
11th to 20thDay
45%41%5%6%31
1520
21st to endDay
46%43%45%2
1520
December1st to 10thDay
43%42%46%5%
1520
11th to 20thDay
49%36%8%5%11
1699
21st to endDay
58%30%6%5%1
2442
January1st to 10thNight
60%29%5%5%
4726
11th to 20thNight
43%28%8%13%6%1
4727
21st to endNight
65%24%45%21
4827
February1st to 10thNight
46%38%7%6%2
2397
11th to 20thNight
40%40%7%8%5%1
2274
21st to endNight
45%37%6%8%31
1901
March1st to 10thNight
42%39%8%9%2
2106
11th to 20thNight
45%38%6%7%3
1980
21st to endNight
46%38%9%7%1
2117
April1st to 10thNight
41%39%10%8%2
1800
11th to 20thNight
37%38%7%11%5%2
1701
21st to endNight
41%39%7%8%5%
1565
May1st to 10thNight
29%42%11%13%6%
1440
11th to 20thNight
26%40%13%13%7%
1416
21st to endNight
35%39%11%11%3
1526
June1st to 10thNight
37%38%11%8%5%2
1260
11th to 20thNight
35%41%13%10%1
1260
21st to endNight
27%38%14%14%5%3
1260
July1st to 10thNight
19%40%10%21%8%3
1225
11th to 20thNight
16%38%12%24%8%1
1218
21st to endNight
10%39%9%22%16%5%
1460
August1st to 10thNight
18%38%13%20%10%1
1437
11th to 20thNight
13%38%15%19%11%5%
1602
21st to endNight
22%39%11%19%8%1
1847
September1st to 10thNight
14%39%11%22%11%4
1800
11th to 20thNight
25%39%9%13%12%2
1800
21st to endNight
29%39%11%14%6%1
2061
October1st to 10thNight
30%38%10%14%8%
2160
11th to 20thNight
35%39%10%13%3
2160
21st to endNight
37%40%8%9%5%
2510
November1st to 10thNight
45%42%46%21
2590
11th to 20thNight
42%42%8%5%3
2660
21st to endNight
43%43%6%6%2
2660
December1st to 10thNight
40%42%7%7%31
2660
11th to 20thNight
53%36%6%32
3501
21st to endNight
56%28%6%8%2
5214

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 10thDay
45%7%18%14%9%7%
180
11th to 20thDay
46%11%12%13%11%7%
180
21st to endDay
50%6%13%14%14%4
218
February1st to 10thDay
43%9%15%18%13%2
353
11th to 20thDay
39%7%18%20%15%2
335
21st to endDay
32%10%20%25%9%3
290
March1st to 10thDay
34%6%22%21%13%4
420
11th to 20thDay
34%8%16%19%18%4
420
21st to endDay
36%9%19%21%14%2
462
April1st to 10thDay
31%11%18%22%16%2
420
11th to 20thDay
25%6%24%23%16%5%
412
21st to endDay
25%7%25%24%15%4
420
May1st to 10thDay
17%6%22%31%21%4
423
11th to 20thDay
21%317%27%25%8%
448
21st to endDay
18%324%29%19%7%
508
June1st to 10thDay
22%423%29%19%4
630
11th to 20thDay
20%5%26%28%18%3
630
21st to endDay
14%421%31%26%5%
630
July1st to 10thDay
14%315%35%28%5%
621
11th to 20thDay
9%418%34%30%5%
618
21st to endDay
7%212%34%35%10%
515
August1st to 10thDay
12%314%28%31%12%
447
11th to 20thDay
9%39%38%31%11%
437
21st to endDay
13%420%29%24%9%
495
September1st to 10thDay
18%418%33%21%6%
450
11th to 20thDay
21%5%16%25%28%6%
450
21st to endDay
25%5%19%22%22%6%
450
October1st to 10thDay
27%418%21%20%8%
450
11th to 20thDay
35%6%12%20%19%8%
450
21st to endDay
37%11%14%19%13%6%
368
November1st to 10thDay
38%8%18%21%13%3
180
11th to 20thDay
41%12%9%11%17%11%
180
21st to endDay
42%6%18%16%8%10%
180
December1st to 10thDay
47%9%14%8%10%12%
180
11th to 20thDay
47%9%13%16%13%2
180
21st to endDay
44%11%16%17%9%3
198
January1st to 10thNight
49%8%16%16%9%3
850
11th to 20thNight
45%6%12%20%15%2
844
21st to endNight
45%5%13%22%13%2
836
February1st to 10thNight
40%7%19%22%11%1
738
11th to 20thNight
37%7%16%25%13%2
704
21st to endNight
36%7%21%22%13%2
592
March1st to 10thNight
35%8%17%21%18%2
720
11th to 20thNight
38%7%16%23%13%3
720
21st to endNight
38%5%14%23%16%4
792
April1st to 10thNight
36%5%13%27%17%3
720
11th to 20thNight
27%7%17%28%17%5%
633
21st to endNight
28%5%17%30%17%3
485
May1st to 10thNight
19%412%30%33%3
360
11th to 20thNight
19%27%28%38%6%
354
21st to endNight
19%38%32%32%5%
389
June1st to 10thNight
24%411%28%29%4
360
11th to 20thNight
18%417%32%26%4
360
21st to endNight
14%311%31%36%6%
360
July1st to 10thNight
13%28%29%43%5%
350
11th to 20thNight
10%28%31%41%8%
348
21st to endNight
5%15%28%52%10%
394
August1st to 10thNight
11%25%20%44%19%
371
11th to 20thNight
9%1423%49%15%
534
21st to endNight
13%29%25%42%10%
659
September1st to 10thNight
12%26%34%37%9%
720
11th to 20thNight
21%313%17%34%12%
720
21st to endNight
24%312%27%28%6%
720
October1st to 10thNight
24%313%24%27%8%
720
11th to 20thNight
34%414%23%19%6%
720
21st to endNight
38%5%15%24%14%4
792
November1st to 10thNight
44%7%16%23%10%
740
11th to 20thNight
43%6%18%19%12%3
760
21st to endNight
41%6%16%21%13%4
760
December1st to 10thNight
36%5%16%25%15%3
760
11th to 20thNight
51%8%15%19%7%1
843
21st to endNight
49%7%19%18%7%1
935
Page generated at 2024-02-02 02:20:33. Version ac07

Copyright 2024 Attilla Danko


White Rock Clear Sky Chart |Charts Home