Halibut Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Halibut Point clear sky chart from 2005-11-05 to 2018-02-22.

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
36%
15512
17%
48853
9%
15479
45%
15479
21%
32438

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
20%
780
15%
2716
5%
776
32%
776
16%
1803
January16th to endNight
16%
832
16%
2912
3%
832
32%
832
15%
1933
February1st to 15thNight
16%
764
14%
2382
3%
761
29%
761
17%
1666
February16th to endNight
23%
659
21%
1976
7%
659
40%
659
21%
1336
March1st to 15thNight
25%
720
16%
2136
8%
720
35%
720
19%
1498
March16th to endNight
26%
768
21%
2060
8%
768
37%
768
24%
1410
April1st to 15thNight
35%
718
18%
1796
7%
718
41%
718
25%
1275
April16th to endNight
41%
566
17%
1646
8%
566
47%
566
22%
1133
May1st to 15thNight
42%
540
14%
1620
8%
540
46%
540
20%
1138
May16th to endNight
46%
439
11%
1561
11%
438
50%
438
17%
1059
June1st to 15thNight
46%
360
12%
1440
15%
360
50%
360
14%
979
June16th to endNight
61%
360
11%
1440
16%
360
63%
360
21%
884
July1st to 15thNight
62%
340
12%
1360
18%
340
63%
340
22%
826
July16th to endNight
67%
376
14%
1418
21%
354
68%
354
21%
892
August1st to 15thNight
66%
529
16%
1599
14%
526
67%
526
28%
1013
August16th to endNight
63%
684
20%
1830
13%
684
65%
684
32%
1174
September1st to 15thNight
57%
720
19%
1881
12%
720
60%
720
35%
1206
September16th to endNight
56%
717
26%
1980
20%
717
61%
717
36%
1210
October1st to 15thNight
44%
720
20%
2010
12%
720
51%
720
27%
1310
October16th to endNight
33%
768
16%
2490
9%
768
44%
768
21%
1634
November1st to 15thNight
33%
760
17%
2472
10%
760
44%
760
21%
1628
November16th to endNight
29%
780
19%
2535
9%
780
41%
780
20%
1620
December1st to 15thNight
21%
780
16%
2681
4%
780
35%
780
16%
1813
December16th to endNight
15%
832
16%
2912
3%
832
31%
832
15%
1998

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
16%6%2442445%7%41%
49398
Night
17%7%25%42445%6%39%
49024
Cloud CoverDay
16%6%2442445%7%41%
49408
Night
17%7%25%42445%6%38%
49029
TransparencyDay
41%6%12%21%14%2
49087
Night
44%6%12%20%14%1
48853
SeeingDay
21%321%32%17%3
6388
Night
20%6%28%28%12%2
15512

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
17%7%3431436%7%39%
1552
16th to endDay
17%7%3442335%7%39%
1664
February1st to 15thDay
19%8%25%5%3446%7%33%
1803
16th to endDay
13%8%36%32445%7%38%
1644
March1st to 15thDay
21%7%3443435%8%33%
1813
16th to endDay
17%6%24424246%43%
2163
April1st to 15thDay
16%6%243245%5%6%41%
2152
16th to endDay
17%42442445%7%43%
2313
May1st to 15thDay
23%7%26%423346%34%
2332
16th to endDay
16%5%2442445%7%40%
2562
June1st to 15thDay
23%5%2442445%7%34%
2520
16th to endDay
14%5%25%5%245%6%8%39%
2520
July1st to 15thDay
11%5%14425%5%6%10%42%
2520
16th to endDay
10%4245%345%6%8%42%
2651
August1st to 15thDay
10%425%4346%6%9%43%
2340
16th to endDay
11%3124235%6%8%50%
2369
September1st to 15thDay
12%5%23423347%50%
2079
16th to endDay
14%313323336%51%
1980
October1st to 15thDay
18%5%24423446%44%
1950
16th to endDay
17%424424346%44%
1731
November1st to 15thDay
21%7%24323336%41%
1716
16th to endDay
17%6%23323447%43%
1755
December1st to 15thDay
19%8%35%5%23345%37%
1605
16th to endDay
24%9%34314436%32%
1664
January1st to 15thNight
17%8%25%43445%7%36%
2716
16th to endNight
17%9%45%43436%7%33%
2912
February1st to 15thNight
16%10%26%5%235%5%7%33%
2381
16th to endNight
17%9%25%4235%46%39%
1976
March1st to 15thNight
20%8%25%42435%6%35%
2123
16th to endNight
17%7%35%5%24335%42%
2060
April1st to 15thNight
18%7%35%4245%45%38%
1796
16th to endNight
21%5%26%435%345%38%
1646
May1st to 15thNight
20%7%25%5%25%446%34%
1620
16th to endNight
20%6%25%5%34447%35%
1559
June1st to 15thNight
25%6%34423447%32%
1440
16th to endNight
15%5%1443445%7%41%
1440
July1st to 15thNight
11%5%35%6%3445%8%41%
1440
16th to endNight
13%5%245%27%45%8%39%
1514
August1st to 15thNight
9%424436%5%6%8%42%
1610
16th to endNight
11%5%245%2446%8%44%
1830
September1st to 15thNight
12%5%245%2345%6%49%
1881
16th to endNight
13%414323346%52%
1980
October1st to 15thNight
17%425%423446%44%
2010
16th to endNight
19%6%15%424346%41%
2490
November1st to 15thNight
17%5%25%434445%41%
2472
16th to endNight
16%7%24423446%41%
2535
December1st to 15thNight
18%8%36%424446%36%
2681
16th to endNight
20%9%25%42436%6%33%
2912

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
17%7%3442345%8%37%
1552
16th to endDay
17%7%26%42336%7%38%
1664
February1st to 15thDay
20%7%245%3446%7%32%
1803
16th to endDay
13%8%345%2447%7%38%
1644
March1st to 15thDay
21%7%25%43445%8%33%
1823
16th to endDay
17%6%24423446%43%
2163
April1st to 15thDay
17%6%2443445%7%41%
2152
16th to endDay
17%424424447%44%
2313
May1st to 15thDay
24%6%26%423346%34%
2332
16th to endDay
16%6%2442445%8%40%
2562
June1st to 15thDay
23%5%2342445%7%34%
2520
16th to endDay
14%425%5%245%6%8%41%
2520
July1st to 15thDay
11%5%144245%6%9%43%
2520
16th to endDay
10%424435%5%6%8%43%
2651
August1st to 15thDay
10%4244345%7%9%44%
2340
16th to endDay
11%312325%5%5%8%49%
2369
September1st to 15thDay
12%5%1442335%6%50%
2079
16th to endDay
14%5%13323346%51%
1980
October1st to 15thDay
19%414423346%44%
1950
16th to endDay
17%5%14423446%43%
1731
November1st to 15thDay
21%8%25%423336%40%
1716
16th to endDay
17%6%24324347%42%
1755
December1st to 15thDay
19%8%35%5%24246%36%
1605
16th to endDay
24%10%34324446%31%
1664
January1st to 15thNight
17%7%35%5%3445%7%34%
2716
16th to endNight
18%9%35%425%35%8%32%
2912
February1st to 15thNight
16%9%35%5%35%46%7%31%
2374
16th to endNight
18%8%245%2335%6%38%
1976
March1st to 15thNight
19%8%35%42445%6%34%
2136
16th to endNight
17%7%25%5%2334442%
2059
April1st to 15thNight
17%8%35%5%25%445%37%
1796
16th to endNight
20%5%35%5%34435%37%
1646
May1st to 15thNight
20%7%26%5%3445%5%34%
1620
16th to endNight
20%6%35%5%25%45%6%35%
1559
June1st to 15thNight
24%6%25%5%24347%33%
1440
16th to endNight
15%5%15%5%2346%8%40%
1440
July1st to 15thNight
10%5%36%6%245%5%8%41%
1440
16th to endNight
12%6%25%436%46%8%39%
1514
August1st to 15thNight
9%425%436%6%6%8%42%
1610
16th to endNight
11%5%245%2436%7%45%
1830
September1st to 15thNight
11%5%1442346%6%48%
1881
16th to endNight
13%423323346%51%
1980
October1st to 15thNight
17%5%24423346%44%
2010
16th to endNight
19%6%24424445%41%
2490
November1st to 15thNight
17%5%25%5%34345%40%
2472
16th to endNight
17%7%345%23447%40%
2535
December1st to 15thNight
19%8%35%4245%5%6%35%
2681
16th to endNight
20%10%345%3335%7%32%
2912

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
42%7%13%23%11%2
1553
16th to endDay
43%5%14%23%11%1
1664
February1st to 15thDay
48%7%13%18%10%
1806
16th to endDay
42%6%14%20%13%2
1644
March1st to 15thDay
49%6%12%18%11%2
1823
16th to endDay
42%411%21%14%5%
2163
April1st to 15thDay
42%5%11%20%16%3
2152
16th to endDay
39%6%10%22%17%3
2313
May1st to 15thDay
50%49%17%15%2
2332
16th to endDay
41%7%14%21%12%1
2566
June1st to 15thDay
48%7%12%20%10%1
2520
16th to endDay
39%8%13%21%14%1
2520
July1st to 15thDay
35%7%14%24%15%1
2371
16th to endDay
35%9%15%22%13%2
2484
August1st to 15thDay
33%10%15%26%13%1
2327
16th to endDay
30%8%13%26%19%1
2369
September1st to 15thDay
34%6%12%23%22%1
2079
16th to endDay
34%49%25%23%2
1980
October1st to 15thDay
40%6%10%24%15%2
1950
16th to endDay
40%5%11%25%14%1
1731
November1st to 15thDay
45%5%12%21%14%1
1716
16th to endDay
41%5%14%21%15%1
1755
December1st to 15thDay
48%415%15%15%
1605
16th to endDay
53%5%12%17%10%1
1664
January1st to 15thNight
46%6%15%18%11%1
2716
16th to endNight
48%5%13%18%13%1
2912
February1st to 15thNight
49%6%13%18%10%1
2382
16th to endNight
45%5%11%22%12%2
1976
March1st to 15thNight
48%6%10%19%13%2
2136
16th to endNight
45%49%16%18%5%
2060
April1st to 15thNight
47%49%18%17%2
1796
16th to endNight
48%48%17%17%3
1646
May1st to 15thNight
50%5%11%15%14%3
1620
16th to endNight
48%7%12%18%10%1
1561
June1st to 15thNight
51%6%10%19%11%
1440
16th to endNight
40%7%12%21%15%1
1440
July1st to 15thNight
39%7%12%25%14%
1360
16th to endNight
41%7%14%24%10%1
1418
August1st to 15thNight
36%8%12%24%14%2
1599
16th to endNight
35%7%11%24%19%
1830
September1st to 15thNight
35%6%12%24%20%1
1881
16th to endNight
33%5%7%25%26%1
1980
October1st to 15thNight
40%5%11%23%15%3
2010
16th to endNight
44%6%12%24%12%
2490
November1st to 15thNight
44%6%13%19%14%2
2472
16th to endNight
42%5%14%21%13%2
2535
December1st to 15thNight
47%6%15%19%10%
2681
16th to endNight
50%5%13%18%11%
2912

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
16%11%34%34%3
90
16th to endDay
28%432%31%4
96
February1st to 15thDay
28%10%34%24%2
294
16th to endDay
15%8%38%28%8%
265
March1st to 15thDay
25%6%35%25%7%
270
16th to endDay
22%7%33%27%9%
288
April1st to 15thDay
21%6%27%31%12%
270
16th to endDay
21%220%39%12%2
270
May1st to 15thDay
32%120%26%14%3
288
16th to endDay
21%112%43%18%3
331
June1st to 15thDay
24%11%35%24%2
315
16th to endDay
15%13%45%22%2
315
July1st to 15thDay
17%17%37%30%6%
305
16th to endDay
12%9%37%35%5%
326
August1st to 15thDay
13%11%35%32%6%
313
16th to endDay
13%6%34%33%11%
332
September1st to 15thDay
19%14%32%25%7%
315
16th to endDay
22%114%29%15%15%
314
October1st to 15thDay
21%220%28%21%5%
307
16th to endDay
19%5%31%27%14%
288
November1st to 15thDay
25%6%23%29%12%2
280
16th to endDay
25%7%28%24%11%2
285
December1st to 15thDay
22%6%33%26%10%
135
16th to endDay
28%5%43%20%2
96
January1st to 15thNight
22%13%41%19%3
780
16th to endNight
22%14%41%18%3
832
February1st to 15thNight
21%11%44%20%1
764
16th to endNight
22%10%40%21%5%
659
March1st to 15thNight
24%9%36%25%4
720
16th to endNight
20%8%35%24%10%
768
April1st to 15thNight
21%431%32%8%
718
16th to endNight
22%324%34%14%1
566
May1st to 15thNight
24%123%34%13%3
540
16th to endNight
24%216%39%16%1
439
June1st to 15thNight
25%215%34%18%3
360
16th to endNight
17%111%48%19%1
360
July1st to 15thNight
11%19%43%29%4
340
16th to endNight
14%16%42%31%2
376
August1st to 15thNight
11%12%43%29%2
529
16th to endNight
15%210%34%30%7%
684
September1st to 15thNight
14%117%36%26%3
720
16th to endNight
17%117%28%24%9%
717
October1st to 15thNight
20%423%31%16%3
720
16th to endNight
22%7%32%27%9%1
768
November1st to 15thNight
20%7%31%26%11%2
760
16th to endNight
21%12%31%24%8%1
780
December1st to 15thNight
23%10%38%21%5%
780
16th to endNight
27%11%39%18%2
832
Page generated at 2018-02-23 11:21:37. Version ac04

Copyright 2018 A. Danko


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