Argyle
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Argyle clear sky chart from 2005-11-05 to 2017-09-10.

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
22%
15035
11%
46597
6%
14990
29%
14990
13%
35244

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
11%
735
7%
2533
2%
731
17%
731
7%
2067
January16th to endNight
9%
768
6%
2496
1%
768
14%
768
5%
2144
February1st to 15thNight
9%
704
5%
2286
0%
701
14%
701
5%
1972
February16th to endNight
15%
631
8%
1976
2%
631
23%
631
10%
1562
March1st to 15thNight
15%
720
13%
2009
5%
720
23%
720
12%
1569
March16th to endNight
20%
768
15%
2112
5%
768
29%
768
17%
1546
April1st to 15thNight
18%
599
14%
1811
5%
599
26%
599
14%
1340
April16th to endNight
24%
540
15%
1620
6%
540
32%
540
18%
1147
May1st to 15thNight
21%
540
11%
1620
5%
540
27%
540
15%
1219
May16th to endNight
27%
561
10%
1504
5%
560
32%
560
17%
1146
June1st to 15thNight
23%
465
8%
1365
4%
465
27%
465
13%
1073
June16th to endNight
32%
360
9%
1260
7%
360
36%
360
14%
914
July1st to 15thNight
36%
346
10%
1196
10%
346
39%
346
15%
869
July16th to endNight
28%
565
8%
1588
7%
532
30%
532
13%
1253
August1st to 15thNight
38%
539
13%
1608
10%
535
40%
535
19%
1143
August16th to endNight
36%
573
17%
1743
10%
573
42%
573
21%
1203
September1st to 15thNight
34%
587
19%
1811
12%
587
42%
587
23%
1195
September16th to endNight
40%
657
23%
1815
15%
657
46%
657
27%
1178
October1st to 15thNight
30%
660
18%
1969
8%
660
39%
660
21%
1334
October16th to endNight
22%
704
15%
2129
6%
704
30%
704
17%
1487
November1st to 15thNight
27%
713
13%
2352
7%
713
34%
713
15%
1686
November16th to endNight
22%
750
11%
2520
6%
750
29%
750
10%
1893
December1st to 15thNight
15%
750
7%
2520
2%
750
21%
750
8%
2024
December16th to endNight
13%
800
8%
2754
2%
800
20%
800
5%
2280

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
22%9%46%5%24345%29%
48015
Night
22%11%47%6%34446%25%
46771
TransparencyDay
56%410%18%9%
47707
Night
59%410%17%7%
46597
SeeingDay
30%14%27%17%7%1
7086
Night
29%12%27%21%7%
15035

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
21%17%6%10%8%36%34313%
1398
16th to endDay
20%13%5%11%10%35%45%5%14%
1728
February1st to 15thDay
16%14%8%12%12%46%5%5%410%
1575
16th to endDay
13%13%8%12%9%34445%21%
1494
March1st to 15thDay
21%11%5%8%7%3333426%
1939
16th to endDay
19%9%5%7%5%33346%30%
2112
April1st to 15thDay
21%11%36%42443432%
2135
16th to endDay
23%8%34323445%36%
2340
May1st to 15thDay
27%9%35%5%23335%31%
2332
16th to endDay
26%8%2442335%6%31%
2607
June1st to 15thDay
29%7%35%434335%29%
2604
16th to endDay
24%7%34423446%33%
2700
July1st to 15thDay
25%7%35%32436%7%30%
2679
16th to endDay
25%9%36%434447%26%
2471
August1st to 15thDay
22%7%24435%45%6%32%
2340
16th to endDay
19%6%2332345%7%40%
2459
September1st to 15thDay
18%5%24423346%44%
2035
16th to endDay
18%6%24422236%44%
1815
October1st to 15thDay
21%6%25%42435%6%38%
1661
16th to endDay
22%9%45%6%24346%28%
1741
November1st to 15thDay
23%9%47%5%3344427%
1506
16th to endDay
22%12%6%9%6%35%5%46%18%
1440
December1st to 15thDay
27%14%7%9%5%25%43414%
1440
16th to endDay
26%13%6%9%6%35%33415%
1464
January1st to 15thNight
20%18%6%11%6%34346%15%
2533
16th to endNight
18%16%6%12%10%5%6%445%11%
2496
February1st to 15thNight
19%14%8%14%10%35%33411%
2285
16th to endNight
15%13%5%10%8%46%5%5%5%20%
1976
March1st to 15thNight
22%9%5%9%7%35%345%24%
1997
16th to endNight
17%10%47%6%34345%31%
2112
April1st to 15thNight
25%11%35%5%23336%28%
1811
16th to endNight
23%9%24424448%30%
1620
May1st to 15thNight
27%10%35%424447%25%
1620
16th to endNight
26%8%35%5%24346%27%
1502
June1st to 15thNight
29%10%45%6%24436%22%
1365
16th to endNight
26%10%35%424345%29%
1260
July1st to 15thNight
27%7%36%5%3436%7%24%
1266
16th to endNight
28%12%46%5%235%45%20%
1695
August1st to 15thNight
22%11%26%423347%31%
1620
16th to endNight
20%8%25%42435%6%36%
1743
September1st to 15thNight
21%6%24333345%40%
1811
16th to endNight
20%5%23323345%44%
1815
October1st to 15thNight
20%7%25%43335%6%37%
1969
16th to endNight
22%8%36%42335%6%33%
2129
November1st to 15thNight
20%9%46%5%345%5%7%27%
2352
16th to endNight
22%12%5%6%6%34446%25%
2520
December1st to 15thNight
26%13%5%8%5%345%5%6%15%
2520
16th to endNight
25%15%5%9%6%35%34416%
2754

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
74%49%9%2
1399
16th to endDay
70%38%14%2
1728
February1st to 15thDay
75%410%7%1
1578
16th to endDay
65%410%15%4
1494
March1st to 15thDay
61%211%15%7%1
1950
16th to endDay
55%111%19%10%1
2112
April1st to 15thDay
54%37%18%13%1
2135
16th to endDay
50%29%22%13%1
2340
May1st to 15thDay
57%37%19%9%2
2332
16th to endDay
53%5%13%18%9%
2611
June1st to 15thDay
58%39%18%8%1
2604
16th to endDay
51%5%11%19%11%
2700
July1st to 15thDay
48%8%12%18%10%1
2521
16th to endDay
55%6%10%18%8%
2315
August1st to 15thDay
50%7%9%21%10%1
2327
16th to endDay
43%5%11%23%14%
2459
September1st to 15thDay
39%5%11%23%18%1
2035
16th to endDay
42%26%28%18%1
1815
October1st to 15thDay
46%311%25%11%1
1661
16th to endDay
56%310%19%8%
1741
November1st to 15thDay
58%310%18%7%1
1506
16th to endDay
67%410%12%4
1440
December1st to 15thDay
72%310%11%2
1440
16th to endDay
72%39%10%4
1464
January1st to 15thNight
69%412%10%3
2533
16th to endNight
74%5%7%10%2
2496
February1st to 15thNight
76%39%8%2
2286
16th to endNight
64%312%14%4
1976
March1st to 15thNight
62%310%14%8%
2009
16th to endNight
54%310%18%13%
2112
April1st to 15thNight
58%27%18%10%2
1811
16th to endNight
52%310%21%10%1
1620
May1st to 15thNight
59%38%18%9%
1620
16th to endNight
56%5%11%18%7%
1504
June1st to 15thNight
63%38%18%4
1365
16th to endNight
57%410%16%11%
1260
July1st to 15thNight
53%7%13%17%8%
1196
16th to endNight
61%6%9%16%5%1
1588
August1st to 15thNight
51%5%9%24%8%
1608
16th to endNight
47%6%9%23%12%
1743
September1st to 15thNight
45%46%27%14%1
1811
16th to endNight
41%36%27%19%1
1815
October1st to 15thNight
47%311%22%12%1
1969
16th to endNight
52%211%23%10%
2129
November1st to 15thNight
54%414%18%7%
2352
16th to endNight
60%413%15%6%
2520
December1st to 15thNight
66%5%12%12%2
2520
16th to endNight
70%5%9%11%3
2754

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
28%24%33%10%3
120
16th to endDay
33%18%33%12%1
256
February1st to 15thDay
27%23%33%12%3
236
16th to endDay
20%22%34%18%3
224
March1st to 15thDay
32%24%26%9%6%
270
16th to endDay
29%22%25%14%6%1
288
April1st to 15thDay
31%22%28%10%6%
270
16th to endDay
27%17%33%13%5%1
270
May1st to 15thDay
36%16%26%14%41
288
16th to endDay
33%14%23%20%6%1
508
June1st to 15thDay
33%10%27%20%6%
495
16th to endDay
34%8%25%20%8%1
495
July1st to 15thDay
30%7%25%22%11%2
475
16th to endDay
31%6%28%22%9%1
332
August1st to 15thDay
26%7%29%22%10%3
313
16th to endDay
24%9%28%20%13%3
332
September1st to 15thDay
24%9%32%23%7%3
294
16th to endDay
22%8%31%20%10%6%
254
October1st to 15thDay
29%9%26%19%9%5%
227
16th to endDay
31%19%27%15%6%
240
November1st to 15thDay
27%16%23%20%9%2
235
16th to endDay
32%15%26%17%5%1
240
December1st to 15thDay
37%17%28%12%3
240
16th to endDay
41%26%17%13%1
184
January1st to 15thNight
31%19%31%14%3
735
16th to endNight
31%19%31%15%2
768
February1st to 15thNight
30%19%32%17%1
704
16th to endNight
27%17%31%16%6%
631
March1st to 15thNight
29%18%28%19%5%
720
16th to endNight
25%16%30%19%6%
768
April1st to 15thNight
33%13%30%19%3
599
16th to endNight
30%11%30%20%7%
540
May1st to 15thNight
32%10%31%19%5%
540
16th to endNight
30%8%28%26%5%1
561
June1st to 15thNight
35%6%25%25%6%
465
16th to endNight
30%424%28%11%
360
July1st to 15thNight
27%323%30%14%
346
16th to endNight
27%6%27%28%9%
565
August1st to 15thNight
24%5%22%33%13%1
539
16th to endNight
23%426%29%14%1
573
September1st to 15thNight
25%6%28%25%11%1
587
16th to endNight
23%8%22%27%15%3
657
October1st to 15thNight
27%10%26%23%10%1
660
16th to endNight
29%14%28%21%5%
704
November1st to 15thNight
25%12%28%22%10%
713
16th to endNight
31%16%23%21%7%
750
December1st to 15thNight
38%15%26%16%3
750
16th to endNight
37%20%23%15%2
800
Page generated at 2017-09-11 20:35:19. Version ac04

Copyright 2017 A. Danko


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