Staveley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Staveley clear sky chart from 2005-11-05 to 2017-09-23.

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
40%
15239
14%
46862
9%
15209
46%
15209
23%
30691

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
30%
900
12%
2685
7%
895
35%
895
17%
1932
January16th to endNight
34%
804
18%
2724
12%
804
43%
804
20%
1791
February1st to 15thNight
36%
698
13%
2389
10%
697
42%
697
17%
1612
February16th to endNight
37%
632
13%
1977
10%
632
43%
632
17%
1416
March1st to 15thNight
30%
720
14%
2106
7%
720
38%
720
20%
1456
March16th to endNight
31%
768
11%
2105
3%
768
38%
768
19%
1545
April1st to 15thNight
32%
625
13%
1705
6%
625
37%
625
21%
1234
April16th to endNight
38%
540
13%
1620
9%
540
43%
540
21%
1124
May1st to 15thNight
42%
456
12%
1464
12%
456
46%
456
24%
941
May16th to endNight
43%
374
7%
1309
6%
374
44%
374
16%
927
June1st to 15thNight
45%
360
3%
1260
1%
360
45%
360
20%
819
June16th to endNight
49%
360
4%
1260
1%
360
50%
360
27%
734
July1st to 15thNight
60%
340
4%
1190
2%
340
62%
340
33%
643
July16th to endNight
64%
376
14%
1293
14%
354
71%
354
38%
639
August1st to 15thNight
67%
427
16%
1499
18%
425
71%
425
32%
811
August16th to endNight
61%
573
26%
1719
21%
573
64%
573
43%
897
September1st to 15thNight
56%
660
20%
1821
13%
660
59%
660
40%
1063
September16th to endNight
48%
688
22%
1903
14%
688
55%
688
38%
1124
October1st to 15thNight
40%
660
17%
1927
9%
660
49%
660
24%
1304
October16th to endNight
43%
704
21%
2288
12%
704
54%
704
26%
1389
November1st to 15thNight
30%
814
19%
2389
10%
814
40%
814
24%
1554
November16th to endNight
31%
900
15%
2649
7%
900
39%
900
23%
1756
December1st to 15thNight
36%
900
13%
2700
8%
900
41%
900
18%
1924
December16th to endNight
32%
960
14%
2880
8%
960
37%
960
17%
2056

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
9%7%36%5%35%5%6%8%38%
48082
Night
7%8%36%5%35%5%6%8%40%
47014
Cloud CoverDay
9%7%36%5%35%5%6%8%38%
48083
Night
7%8%36%5%35%5%6%8%39%
47017
TransparencyDay
41%7%17%21%9%1
47738
Night
41%7%16%22%10%1
46862
SeeingDay
14%10%28%27%15%3
6021
Night
11%8%31%32%14%1
15246

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 15thDay
5%8%5%8%6%35%5%6%7%38%
1253
16th to endDay
47%47%8%47%5%6%9%33%
1512
February1st to 15thDay
6%9%46%6%47%5%7%8%33%
1473
16th to endDay
413%5%9%7%35%5%7%7%29%
1497
March1st to 15thDay
310%47%6%36%5%6%10%34%
1854
16th to endDay
9%11%47%6%37%5%6%7%28%
2117
April1st to 15thDay
11%11%48%6%35%6%5%7%28%
2242
16th to endDay
13%10%36%6%25%5%6%8%31%
2340
May1st to 15thDay
12%6%36%6%46%5%6%6%36%
2484
16th to endDay
21%6%37%5%35%5%5%7%27%
2802
June1st to 15thDay
17%7%25%6%35%6%6%7%30%
2700
16th to endDay
12%5%245%46%5%7%8%37%
2700
July1st to 15thDay
8%314435%5%6%9%46%
2700
16th to endDay
43133245%6%8%54%
2784
August1st to 15thDay
9%3134346%6%9%46%
2452
16th to endDay
8%31442345%7%54%
2483
September1st to 15thDay
13%5%14333345%51%
2139
16th to endDay
10%5%1443345%7%49%
1893
October1st to 15thDay
12%8%38%4345%37%37%
1700
16th to endDay
5%8%36%5%35%6%7%9%36%
1584
November1st to 15thDay
8%7%35%6%45%5%5%7%39%
1458
16th to endDay
410%5%7%42445%11%38%
1311
December1st to 15thDay
48%5%11%8%5%7%5%6%7%30%
1260
16th to endDay
311%48%5%37%6%7%8%33%
1344
January1st to 15thNight
411%6%8%7%36%6%6%9%31%
2685
16th to endNight
410%36%5%35%6%7%8%37%
2724
February1st to 15thNight
5%10%48%7%45%5%48%36%
2378
16th to endNight
5%10%6%9%7%36%7%5%6%31%
1977
March1st to 15thNight
38%5%8%7%46%6%6%10%32%
2106
16th to endNight
7%11%47%6%35%5%7%9%30%
2102
April1st to 15thNight
10%11%46%5%35%46%7%34%
1705
16th to endNight
12%9%36%425%6%5%6%36%
1620
May1st to 15thNight
10%8%37%425%5%47%41%
1463
16th to endNight
19%6%35%5%45%5%5%7%32%
1309
June1st to 15thNight
15%5%25%5%35%45%8%38%
1260
16th to endNight
10%5%135%25%5%6%8%45%
1260
July1st to 15thNight
5%215%5%2447%7%51%
1260
16th to endNight
32124236%6%9%57%
1382
August1st to 15thNight
7%314325%46%8%52%
1507
16th to endNight
6%41321245%8%60%
1719
September1st to 15thNight
11%414322245%56%
1821
16th to endNight
10%414323347%52%
1903
October1st to 15thNight
12%6%35%5%345%6%8%38%
1927
16th to endNight
8%7%335%25%46%8%44%
2288
November1st to 15thNight
5%8%35%5%35%5%5%8%43%
2389
16th to endNight
5%9%6%6%5%3447%9%38%
2649
December1st to 15thNight
39%48%7%38%6%6%8%32%
2700
16th to endNight
410%5%10%8%35%6%6%7%30%
2880

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
5%9%5%8%6%25%47%7%37%
1253
16th to endDay
5%7%47%7%46%5%7%9%33%
1512
February1st to 15thDay
6%10%45%6%5%6%5%6%8%33%
1473
16th to endDay
5%12%6%8%8%345%7%8%28%
1497
March1st to 15thDay
310%47%6%46%5%5%10%34%
1854
16th to endDay
10%11%5%7%7%36%5%5%8%28%
2118
April1st to 15thDay
11%12%37%5%36%5%6%7%28%
2242
16th to endDay
13%9%36%5%25%5%6%8%32%
2340
May1st to 15thDay
12%7%35%446%46%8%36%
2484
16th to endDay
21%7%26%6%35%5%6%7%27%
2802
June1st to 15thDay
17%7%35%6%36%5%6%7%30%
2700
16th to endDay
12%5%245%35%5%7%9%37%
2700
July1st to 15thDay
8%314435%5%5%9%47%
2700
16th to endDay
43133245%6%8%55%
2784
August1st to 15thDay
8%413435%6%7%9%46%
2452
16th to endDay
8%32333345%8%54%
2483
September1st to 15thDay
13%5%14334345%52%
2139
16th to endDay
10%4145%24447%49%
1893
October1st to 15thDay
13%8%27%5%345%47%37%
1700
16th to endDay
6%8%26%5%35%5%7%10%36%
1584
November1st to 15thDay
8%7%36%6%36%5%6%7%38%
1458
16th to endDay
410%47%42445%10%39%
1311
December1st to 15thDay
48%5%11%8%5%7%5%5%7%29%
1260
16th to endDay
411%5%9%437%6%6%8%32%
1344
January1st to 15thNight
411%5%9%6%35%5%6%9%30%
2685
16th to endNight
49%46%6%35%6%6%8%37%
2724
February1st to 15thNight
5%10%48%6%3445%9%36%
2378
16th to endNight
5%10%6%10%7%46%5%5%7%30%
1977
March1st to 15thNight
39%5%8%7%46%5%6%10%31%
2106
16th to endNight
8%11%5%7%6%35%5%7%8%30%
2105
April1st to 15thNight
10%11%46%5%35%46%6%33%
1705
16th to endNight
12%9%36%5%26%5%5%5%36%
1620
May1st to 15thNight
10%8%36%435%447%41%
1463
16th to endNight
19%5%345%36%5%5%7%31%
1309
June1st to 15thNight
15%5%345%45%45%7%38%
1260
16th to endNight
10%4325%345%6%8%46%
1260
July1st to 15thNight
5%3145%1446%8%52%
1260
16th to endNight
42124245%7%8%56%
1382
August1st to 15thNight
6%323335%5%5%9%51%
1507
16th to endNight
6%31232335%7%60%
1719
September1st to 15thNight
11%424313236%56%
1821
16th to endNight
10%42332335%7%52%
1903
October1st to 15thNight
11%7%35%5%35%5%6%7%38%
1927
16th to endNight
8%7%24425%47%7%44%
2288
November1st to 15thNight
5%7%35%5%35%46%8%43%
2389
16th to endNight
5%10%5%6%5%3447%9%37%
2649
December1st to 15thNight
39%5%9%7%46%7%6%8%32%
2700
16th to endNight
412%5%9%8%35%5%6%7%30%
2880

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
44%7%16%22%6%2
1253
16th to endDay
44%8%16%18%9%3
1512
February1st to 15thDay
47%8%16%18%7%1
1473
16th to endDay
51%7%17%17%6%
1497
March1st to 15thDay
44%9%20%18%7%
1854
16th to endDay
51%6%17%17%6%
2118
April1st to 15thDay
52%6%15%16%7%1
2242
16th to endDay
47%8%15%19%7%1
2340
May1st to 15thDay
43%6%15%23%10%
2484
16th to endDay
53%7%15%16%6%
2807
June1st to 15thDay
48%8%17%17%7%1
2700
16th to endDay
39%8%19%23%8%1
2700
July1st to 15thDay
31%8%18%28%11%1
2541
16th to endDay
25%8%19%26%16%3
2610
August1st to 15thDay
29%9%23%26%8%1
2435
16th to endDay
27%6%15%31%16%2
2483
September1st to 15thDay
34%413%24%17%6%
2139
16th to endDay
33%5%12%30%13%3
1893
October1st to 15thDay
45%8%15%20%8%1
1700
16th to endDay
39%9%17%23%8%1
1584
November1st to 15thDay
43%9%15%22%9%
1458
16th to endDay
40%6%20%20%9%2
1311
December1st to 15thDay
53%8%13%17%5%
1260
16th to endDay
46%8%15%20%8%1
1344
January1st to 15thNight
48%8%17%16%6%2
2685
16th to endNight
41%8%15%19%11%2
2724
February1st to 15thNight
45%8%14%19%10%1
2389
16th to endNight
51%6%13%19%8%
1977
March1st to 15thNight
44%8%19%20%6%
2106
16th to endNight
49%8%16%19%5%
2105
April1st to 15thNight
47%8%13%20%10%
1705
16th to endNight
46%7%14%23%7%1
1620
May1st to 15thNight
42%5%13%26%11%1
1464
16th to endNight
49%9%14%18%6%1
1309
June1st to 15thNight
44%7%15%22%9%
1260
16th to endNight
33%8%19%25%12%1
1260
July1st to 15thNight
27%7%19%29%12%2
1190
16th to endNight
21%9%18%29%16%6%
1293
August1st to 15thNight
28%7%18%28%14%2
1499
16th to endNight
22%6%11%33%21%4
1719
September1st to 15thNight
30%313%24%21%6%
1821
16th to endNight
30%5%16%27%15%4
1903
October1st to 15thNight
42%7%16%20%10%1
1927
16th to endNight
35%8%16%26%12%
2288
November1st to 15thNight
37%9%16%22%13%
2389
16th to endNight
41%7%21%16%10%3
2649
December1st to 15thNight
47%9%16%18%7%
2700
16th to endNight
50%6%15%20%6%
2880

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%123%20%16%21%
60
16th to endDay
14%6%35%21%12%9%
64
February1st to 15thDay
12%15%32%24%13%1
73
16th to endDay
12%8%39%28%10%
156
March1st to 15thDay
10%20%47%16%4
270
16th to endDay
15%19%41%16%6%1
288
April1st to 15thDay
18%19%29%24%8%
269
16th to endDay
20%13%27%26%10%1
270
May1st to 15thDay
15%10%29%25%16%3
360
16th to endDay
23%7%19%25%18%5%
517
June1st to 15thDay
14%11%24%28%17%2
495
16th to endDay
14%8%26%29%17%3
495
July1st to 15thDay
9%425%32%22%5%
475
16th to endDay
7%5%33%31%16%4
453
August1st to 15thDay
10%7%19%33%22%6%
315
16th to endDay
9%10%27%28%16%7%
332
September1st to 15thDay
19%10%22%27%16%3
315
16th to endDay
12%15%32%23%10%4
284
October1st to 15thDay
17%12%29%23%15%1
151
16th to endDay
17%416%33%19%8%
96
November1st to 15thDay
17%17%35%20%6%2
90
16th to endDay
5%10%28%28%13%13%
69
December1st to 15thDay
311%31%31%18%3
60
16th to endDay
9%435%20%23%6%
64
January1st to 15thNight
10%15%34%28%10%1
900
16th to endNight
10%10%36%29%12%1
804
February1st to 15thNight
9%11%30%28%15%4
704
16th to endNight
10%6%32%33%14%2
632
March1st to 15thNight
9%9%40%29%10%
720
16th to endNight
13%10%33%33%7%1
768
April1st to 15thNight
15%9%34%29%9%1
625
16th to endNight
19%7%27%33%13%
540
May1st to 15thNight
13%6%28%31%18%
456
16th to endNight
21%5%21%31%19%
375
June1st to 15thNight
18%5%27%30%16%1
360
16th to endNight
12%326%36%20%
360
July1st to 15thNight
7%220%40%28%
340
16th to endNight
4124%45%21%2
376
August1st to 15thNight
8%214%41%30%2
427
16th to endNight
8%422%41%21%1
573
September1st to 15thNight
14%321%32%25%3
660
16th to endNight
12%428%34%15%4
688
October1st to 15thNight
16%6%27%29%16%3
660
16th to endNight
12%6%31%33%14%1
704
November1st to 15thNight
9%16%39%26%6%1
814
16th to endNight
11%9%40%28%8%2
900
December1st to 15thNight
9%8%33%33%11%2
900
16th to endNight
10%10%33%32%10%2
960
Page generated at 2017-09-24 07:15:50. Version ac04

Copyright 2017 A. Danko


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