Arvada
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Arvada clear sky chart from 2005-11-05 to 2018-01-12.

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
54%
16466
28%
48367
18%
16425
64%
16425
42%
26177

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
42%
953
31%
2662
15%
951
57%
951
48%
1400
January16th to endNight
38%
810
33%
2538
18%
810
56%
810
41%
1334
February1st to 15thNight
35%
699
25%
2247
11%
698
52%
698
37%
1230
February16th to endNight
37%
632
32%
1894
15%
632
54%
632
38%
1047
March1st to 15thNight
44%
720
28%
2115
13%
720
57%
720
44%
1142
March16th to endNight
44%
678
28%
2022
15%
678
56%
678
39%
1105
April1st to 15thNight
43%
539
24%
1798
16%
539
57%
539
36%
956
April16th to endNight
44%
540
23%
1800
17%
540
55%
540
29%
1059
May1st to 15thNight
54%
540
19%
1603
16%
540
58%
540
29%
1023
May16th to endNight
61%
563
18%
1498
13%
561
66%
561
37%
895
June1st to 15thNight
71%
540
21%
1440
17%
540
73%
540
49%
775
June16th to endNight
78%
540
27%
1440
22%
540
81%
540
57%
728
July1st to 15thNight
75%
510
17%
1360
15%
510
76%
510
37%
814
July16th to endNight
81%
564
26%
1441
24%
531
81%
531
45%
793
August1st to 15thNight
77%
539
20%
1668
20%
536
79%
536
40%
885
August16th to endNight
78%
573
29%
1910
33%
573
80%
573
41%
985
September1st to 15thNight
73%
540
28%
1800
30%
540
77%
540
40%
928
September16th to endNight
72%
537
36%
1932
35%
537
80%
537
47%
875
October1st to 15thNight
57%
708
29%
2148
20%
708
64%
708
43%
1137
October16th to endNight
57%
801
35%
2337
20%
801
67%
801
48%
1215
November1st to 15thNight
55%
950
33%
2470
17%
950
63%
950
53%
1323
November16th to endNight
52%
975
35%
2602
18%
975
63%
975
52%
1371
December1st to 15thNight
42%
975
26%
2730
10%
975
55%
975
44%
1484
December16th to endNight
43%
1040
27%
2912
13%
1040
56%
1040
40%
1673

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
5%42332446%8%53%
48981
Night
5%42332335%7%59%
48542
Cloud CoverDay
5%4143245%6%8%53%
48979
Night
4423323347%58%
48542
TransparencyDay
27%6%12%24%21%8%
48658
Night
24%5%11%25%23%8%
48367
SeeingDay
9%7%25%31%20%6%
6210
Night
6%329%41%17%2
16474

By Month

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
16%23312248%61%
1520
16th to endDay
15%23212347%64%
1695
February1st to 15thDay
25%25%42445%7%54%
1613
16th to endDay
16%24424347%57%
1580
March1st to 15thDay
442441435%9%55%
1842
16th to endDay
6%5%333245%6%8%51%
2202
April1st to 15thDay
8%5%1332335%8%55%
2150
16th to endDay
12%6%234245%5%7%45%
2160
May1st to 15thDay
12%5%24435%5%7%7%42%
2343
16th to endDay
10%423425%6%6%9%43%
2616
June1st to 15thDay
6%212435%5%7%8%51%
2520
16th to endDay
322325%6%8%9%54%
2520
July1st to 15thDay
7%314426%6%7%10%45%
2520
16th to endDay
5%324425%5%7%10%47%
2626
August1st to 15thDay
6%314447%7%7%10%42%
2283
16th to endDay
5%313435%6%6%9%50%
2292
September1st to 15thDay
7%31332345%7%56%
2160
16th to endDay
5%313312346%63%
2026
October1st to 15thDay
6%31232335%7%60%
1809
16th to endDay
5%412112236%66%
1875
November1st to 15thDay
131331245%9%61%
1718
16th to endDay
232322236%8%62%
1687
December1st to 15thDay
15%25%42235%8%58%
1560
16th to endDay
35%23324347%57%
1664
January1st to 15thNight
1333313347%64%
2662
16th to endNight
25%34422335%62%
2538
February1st to 15thNight
17%25%324346%57%
2237
16th to endNight
28%24413345%58%
1894
March1st to 15thNight
35%2342335%6%58%
2115
16th to endNight
6%6%23312347%58%
2022
April1st to 15thNight
7%6%2222245%7%56%
1798
16th to endNight
14%6%24322436%50%
1800
May1st to 15thNight
13%6%24224448%45%
1602
16th to endNight
8%31332445%7%55%
1497
June1st to 15thNight
5%31221345%10%60%
1440
16th to endNight
311111346%9%65%
1440
July1st to 15thNight
5%213435%5%6%10%50%
1440
16th to endNight
4113225%5%7%9%55%
1539
August1st to 15thNight
42133335%7%10%54%
1677
16th to endNight
421342446%8%57%
1910
September1st to 15thNight
8%21231335%7%58%
1800
16th to endNight
6%12322335%66%
1932
October1st to 15thNight
8%412213345%62%
2148
16th to endNight
5%413312236%63%
2337
November1st to 15thNight
3313223346%65%
2470
16th to endNight
3423212347%65%
2602
December1st to 15thNight
25%24413248%59%
2730
16th to endNight
27%2432345%7%55%
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
16%23313247%62%
1520
16th to endDay
15%23223247%63%
1695
February1st to 15thDay
15%36%324447%54%
1613
16th to endDay
25%3441435%8%56%
1580
March1st to 15thDay
342441435%9%54%
1842
16th to endDay
6%6%233245%5%8%52%
2200
April1st to 15thDay
7%5%1432345%8%54%
2150
16th to endDay
11%6%1432446%7%45%
2160
May1st to 15thDay
11%5%14425%5%7%8%41%
2343
16th to endDay
9%415%4345%7%9%43%
2616
June1st to 15thDay
5%313435%6%7%8%50%
2520
16th to endDay
213325%7%8%9%53%
2520
July1st to 15thDay
6%3145%35%7%8%9%45%
2520
16th to endDay
4314425%6%7%10%47%
2626
August1st to 15thDay
5%315%5%36%6%8%10%42%
2283
16th to endDay
4213435%6%7%9%50%
2292
September1st to 15thDay
7%31332346%6%57%
2160
16th to endDay
5%313313446%62%
2026
October1st to 15thDay
6%313313347%59%
1809
16th to endDay
5%5%12213326%66%
1875
November1st to 15thDay
131431236%8%60%
1718
16th to endDay
232322245%8%62%
1687
December1st to 15thDay
15%35%32335%9%56%
1560
16th to endDay
36%24323348%56%
1664
January1st to 15thNight
1333323347%63%
2662
16th to endNight
25%24423335%61%
2538
February1st to 15thNight
27%35%324347%55%
2237
16th to endNight
28%35%423445%57%
1894
March1st to 15thNight
35%2342345%7%58%
2115
16th to endNight
6%6%23322348%56%
2022
April1st to 15thNight
7%5%2232335%7%55%
1798
16th to endNight
13%6%24323346%49%
1800
May1st to 15thNight
13%5%26%32445%7%45%
1602
16th to endNight
7%414324447%54%
1497
June1st to 15thNight
43221445%9%59%
1440
16th to endNight
21112135%6%8%64%
1440
July1st to 15thNight
5%2235%35%5%6%10%48%
1440
16th to endNight
32123245%7%9%55%
1539
August1st to 15thNight
33124245%6%10%54%
1677
16th to endNight
4234345%5%9%55%
1910
September1st to 15thNight
8%21322435%7%57%
1800
16th to endNight
6%22312345%66%
1932
October1st to 15thNight
8%422212245%61%
2148
16th to endNight
5%413312236%62%
2337
November1st to 15thNight
3214212447%64%
2470
16th to endNight
3423212337%64%
2602
December1st to 15thNight
26%34322348%58%
2730
16th to endNight
37%3341436%7%54%
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
22%312%32%23%5%
1521
16th to endDay
20%39%35%22%7%
1695
February1st to 15thDay
28%5%14%32%15%4
1614
16th to endDay
25%5%8%27%27%5%
1580
March1st to 15thDay
26%5%10%26%23%7%
1842
16th to endDay
29%6%14%22%21%6%
2202
April1st to 15thDay
28%5%12%25%20%7%
2150
16th to endDay
35%7%13%21%18%4
2160
May1st to 15thDay
38%7%14%21%14%3
2343
16th to endDay
35%7%15%23%12%6%
2620
June1st to 15thDay
27%8%14%20%19%10%
2520
16th to endDay
20%7%12%21%28%10%
2520
July1st to 15thDay
31%8%12%19%16%11%
2371
16th to endDay
28%8%15%23%16%7%
2461
August1st to 15thDay
32%8%14%18%16%9%
2268
16th to endDay
26%6%11%23%23%7%
2292
September1st to 15thDay
25%5%9%22%21%15%
2160
16th to endDay
22%47%22%34%8%
2026
October1st to 15thDay
23%5%12%19%28%10%
1809
16th to endDay
20%38%26%28%11%
1875
November1st to 15thDay
20%310%27%26%11%
1718
16th to endDay
19%38%25%32%10%
1687
December1st to 15thDay
25%5%10%31%21%5%
1560
16th to endDay
26%5%13%25%22%6%
1664
January1st to 15thNight
20%5%10%31%26%5%
2662
16th to endNight
26%37%28%25%8%
2538
February1st to 15thNight
28%5%10%31%19%4
2247
16th to endNight
27%5%5%27%24%9%
1894
March1st to 15thNight
24%49%25%27%7%
2115
16th to endNight
27%410%26%25%5%
2022
April1st to 15thNight
26%6%11%24%21%8%
1798
16th to endNight
35%5%10%24%18%5%
1800
May1st to 15thNight
37%7%14%21%14%4
1603
16th to endNight
28%8%19%23%13%6%
1498
June1st to 15thNight
20%6%17%27%15%11%
1440
16th to endNight
14%6%12%22%30%12%
1440
July1st to 15thNight
27%9%14%21%16%10%
1360
16th to endNight
21%8%15%28%17%7%
1441
August1st to 15thNight
24%7%16%24%17%8%
1668
16th to endNight
24%6%11%23%26%8%
1910
September1st to 15thNight
25%5%12%22%19%14%
1800
16th to endNight
20%38%26%32%8%
1932
October1st to 15thNight
24%5%11%19%27%11%
2148
16th to endNight
23%38%24%28%11%
2337
November1st to 15thNight
19%48%26%28%12%
2470
16th to endNight
20%38%25%31%10%
2602
December1st to 15thNight
24%413%29%21%7%
2730
16th to endNight
27%5%14%25%21%3
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
5%8%24%43%13%4
123
16th to endDay
7%332%38%15%3
96
February1st to 15thDay
6%8%43%37%3
90
16th to endDay
4438%37%13%1
81
March1st to 15thDay
415%28%37%12%1
132
16th to endDay
14%25%30%23%4
288
April1st to 15thDay
13%18%34%20%10%3
269
16th to endDay
21%18%34%17%7%1
270
May1st to 15thDay
15%7%27%31%15%2
423
16th to endDay
15%7%22%29%17%8%
517
June1st to 15thDay
7%423%31%24%8%
495
16th to endDay
3423%32%26%9%
495
July1st to 15thDay
10%216%26%33%10%
475
16th to endDay
5%314%27%37%11%
485
August1st to 15thDay
8%5%25%31%20%8%
315
16th to endDay
8%320%36%23%7%
332
September1st to 15thDay
7%427%33%20%7%
315
16th to endDay
6%425%33%20%8%
181
October1st to 15thDay
7%320%37%22%8%
135
16th to endDay
8%7%25%30%21%6%
144
November1st to 15thDay
1323%40%22%8%
135
16th to endDay
8%8%30%39%13%
135
December1st to 15thDay
6%8%43%30%9%
135
16th to endDay
3435%45%8%2
144
January1st to 15thNight
3344%37%9%2
956
16th to endNight
5%445%35%8%1
810
February1st to 15thNight
5%246%37%6%
704
16th to endNight
6%444%38%5%
632
March1st to 15thNight
4242%37%11%
720
16th to endNight
8%6%35%41%7%
678
April1st to 15thNight
10%6%35%38%7%
539
16th to endNight
16%5%29%35%12%
540
May1st to 15thNight
16%318%44%15%1
540
16th to endNight
9%220%41%23%2
563
June1st to 15thNight
5%216%49%22%2
540
16th to endNight
314%47%32%1
540
July1st to 15thNight
6%17%38%40%3
510
16th to endNight
45%39%46%3
564
August1st to 15thNight
5%8%42%39%2
539
16th to endNight
5%8%43%38%4
573
September1st to 15thNight
8%110%44%28%6%
540
16th to endNight
5%16%45%27%5%
537
October1st to 15thNight
11%224%40%16%3
708
16th to endNight
8%324%43%17%2
801
November1st to 15thNight
4331%44%14%1
950
16th to endNight
5%234%45%10%1
975
December1st to 15thNight
5%441%40%7%
975
16th to endNight
6%339%40%8%1
1040
Page generated at 2018-01-12 20:01:25. Version ac04

Copyright 2018 A. Danko


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