Dirt Hills and Cactus Hills
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dirt Hills and Cactus Hills clear sky chart from 2005-11-05 to 2017-09-16.

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
37%
15801
13%
46692
8%
15763
42%
15763
22%
32032

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
26%
895
9%
2652
4%
895
31%
895
16%
1944
January16th to endNight
21%
960
12%
2688
5%
960
28%
960
15%
2034
February1st to 15thNight
29%
765
9%
2357
6%
765
33%
765
14%
1775
February16th to endNight
35%
632
12%
1989
7%
632
41%
632
15%
1505
March1st to 15thNight
33%
720
13%
2136
7%
720
39%
720
20%
1510
March16th to endNight
31%
675
12%
2019
7%
675
37%
675
15%
1529
April1st to 15thNight
37%
539
15%
1798
10%
539
44%
539
23%
1148
April16th to endNight
37%
540
14%
1578
9%
540
42%
540
21%
1112
May1st to 15thNight
42%
540
13%
1440
6%
540
46%
540
29%
957
May16th to endNight
40%
563
9%
1498
6%
561
41%
561
22%
1069
June1st to 15thNight
40%
408
5%
1191
3%
408
42%
408
28%
759
June16th to endNight
52%
360
5%
1124
4%
360
56%
360
32%
651
July1st to 15thNight
60%
340
6%
1190
6%
340
63%
340
36%
624
July16th to endNight
62%
550
15%
1402
9%
517
64%
517
48%
759
August1st to 15thNight
61%
539
17%
1432
11%
536
65%
536
43%
829
August16th to endNight
61%
573
26%
1784
20%
573
68%
573
44%
905
September1st to 15thNight
57%
540
19%
1800
18%
540
63%
540
32%
1037
September16th to endNight
48%
531
23%
1798
21%
531
56%
531
31%
1032
October1st to 15thNight
40%
660
20%
1980
12%
660
48%
660
26%
1254
October16th to endNight
33%
836
18%
2244
7%
836
41%
836
24%
1557
November1st to 15thNight
27%
875
16%
2414
7%
875
34%
875
21%
1701
November16th to endNight
24%
900
14%
2529
5%
900
31%
900
17%
1902
December1st to 15thNight
26%
900
7%
2700
4%
900
29%
900
10%
2197
December16th to endNight
25%
960
10%
2949
4%
960
32%
960
13%
2242

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
11%8%36%6%35%5%5%7%35%
48079
Night
9%8%47%6%35%5%5%7%36%
46850
Cloud CoverDay
11%8%36%6%35%5%5%7%35%
48080
Night
9%8%47%6%35%5%5%7%36%
46852
TransparencyDay
46%6%14%22%8%
47741
Night
45%6%14%21%9%1
46692
SeeingDay
15%8%28%29%15%3
6186
Night
13%7%32%32%12%1
15814

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
8%11%7%9%8%46%6%46%26%
1283
16th to endDay
5%9%6%11%8%5%6%5%6%8%25%
1536
February1st to 15thDay
8%9%7%13%10%5%7%5%5%422%
1518
16th to endDay
6%13%7%11%10%6%7%5%6%5%19%
1485
March1st to 15thDay
8%11%7%10%7%5%5%5%6%8%21%
1821
16th to endDay
11%11%5%9%6%35%5%6%9%24%
2204
April1st to 15thDay
11%9%46%6%36%5%5%7%32%
2150
16th to endDay
17%10%36%6%2445%7%30%
2381
May1st to 15thDay
13%8%26%6%3445%7%36%
2511
16th to endDay
20%6%35%5%35%5%5%7%29%
2616
June1st to 15thDay
20%6%35%6%26%46%7%30%
2763
16th to endDay
12%5%246%35%6%5%8%38%
2832
July1st to 15thDay
8%3245%35%5%5%8%49%
2700
16th to endDay
6%32342445%8%54%
2669
August1st to 15thDay
11%4145%35%5%5%8%45%
2520
16th to endDay
8%41442345%7%53%
2416
September1st to 15thDay
13%5%24323346%49%
2160
16th to endDay
14%5%1442335%7%48%
1849
October1st to 15thDay
16%10%35%423346%39%
1650
16th to endDay
11%11%5%6%42445%7%34%
1617
November1st to 15thDay
10%8%48%5%2445%5%38%
1441
16th to endDay
10%12%47%7%46%5%5%7%28%
1428
December1st to 15thDay
6%15%7%13%11%6%8%5%5%5%15%
1260
16th to endDay
8%12%5%12%11%5%7%5%45%21%
1269
January1st to 15thNight
6%10%6%8%7%47%6%7%7%27%
2652
16th to endNight
5%11%5%9%8%36%6%7%8%25%
2688
February1st to 15thNight
8%11%6%9%9%45%6%47%26%
2346
16th to endNight
6%10%6%10%9%46%6%5%6%25%
1989
March1st to 15thNight
7%8%5%8%7%46%5%5%8%32%
2136
16th to endNight
11%11%5%10%7%445%5%6%27%
2016
April1st to 15thNight
9%7%35%5%35%46%8%39%
1798
16th to endNight
14%10%344345%6%8%34%
1578
May1st to 15thNight
12%7%244245%6%7%41%
1439
16th to endNight
19%6%35%5%345%5%9%32%
1498
June1st to 15thNight
16%3244245%5%8%42%
1191
16th to endNight
9%5%234235%5%10%47%
1124
July1st to 15thNight
6%3133245%5%9%54%
1260
16th to endNight
4233145%6%7%60%
1497
August1st to 15thNight
7%31322435%9%56%
1440
16th to endNight
7%312312346%61%
1784
September1st to 15thNight
10%414434446%51%
1800
16th to endNight
11%5%13423446%51%
1798
October1st to 15thNight
13%7%25%332347%45%
1980
16th to endNight
8%12%47%5%3446%7%36%
2244
November1st to 15thNight
10%11%47%5%34346%39%
2414
16th to endNight
9%10%5%9%7%46%45%8%28%
2529
December1st to 15thNight
10%13%6%12%10%5%6%5%5%5%18%
2700
16th to endNight
7%11%5%11%9%45%6%46%24%
2949

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
7%11%7%9%8%46%7%45%26%
1283
16th to endDay
410%6%11%8%46%5%7%8%25%
1536
February1st to 15thDay
8%9%7%14%8%5%8%6%4423%
1518
16th to endDay
6%13%7%11%10%5%7%6%6%5%19%
1485
March1st to 15thDay
8%11%7%10%8%5%46%6%7%22%
1821
16th to endDay
11%11%5%8%7%45%6%6%9%24%
2205
April1st to 15thDay
10%10%46%6%35%5%6%7%32%
2150
16th to endDay
18%9%37%5%2445%7%30%
2381
May1st to 15thDay
13%7%26%6%345%6%6%36%
2511
16th to endDay
20%7%345%35%5%5%7%29%
2616
June1st to 15thDay
20%6%25%5%35%5%6%7%30%
2763
16th to endDay
12%5%25%5%36%6%5%8%38%
2832
July1st to 15thDay
8%315%43445%8%49%
2700
16th to endDay
6%41342446%8%53%
2669
August1st to 15thDay
11%4145%35%5%5%7%45%
2520
16th to endDay
9%41432345%7%53%
2416
September1st to 15thDay
14%5%24423336%48%
2160
16th to endDay
14%5%14423347%48%
1849
October1st to 15thDay
16%9%46%413346%39%
1650
16th to endDay
11%12%46%5%2445%7%34%
1617
November1st to 15thDay
9%8%5%8%6%25%446%38%
1441
16th to endDay
10%11%5%7%7%45%5%5%7%28%
1428
December1st to 15thDay
7%15%6%13%10%7%7%5%6%5%14%
1260
16th to endDay
9%12%5%12%11%5%7%5%45%20%
1269
January1st to 15thNight
5%11%5%8%7%38%5%7%7%27%
2652
16th to endNight
5%11%5%10%7%36%6%7%8%25%
2688
February1st to 15thNight
7%13%5%9%8%46%5%5%6%26%
2346
16th to endNight
6%11%5%11%9%5%7%5%5%7%25%
1989
March1st to 15thNight
6%8%5%8%8%46%46%7%32%
2136
16th to endNight
11%11%5%9%7%45%45%7%27%
2019
April1st to 15thNight
9%7%36%4345%6%8%39%
1798
16th to endNight
14%9%45%335%5%6%6%35%
1578
May1st to 15thNight
12%7%23425%5%7%7%41%
1439
16th to endNight
19%6%25%5%25%5%5%7%34%
1497
June1st to 15thNight
15%42342346%8%42%
1191
16th to endNight
9%4234245%5%9%48%
1124
July1st to 15thNight
6%41232446%9%54%
1260
16th to endNight
5%133135%5%8%60%
1497
August1st to 15thNight
7%31232435%8%56%
1440
16th to endNight
6%313322347%61%
1784
September1st to 15thNight
10%414424445%52%
1800
16th to endNight
11%5%134335%46%51%
1798
October1st to 15thNight
13%7%15%323348%45%
1980
16th to endNight
9%11%5%6%5%3446%8%35%
2244
November1st to 15thNight
10%11%5%6%6%24346%38%
2414
16th to endNight
9%10%5%9%7%47%448%27%
2529
December1st to 15thNight
9%12%7%13%9%5%6%5%5%5%18%
2700
16th to endNight
7%11%5%11%9%5%5%6%6%6%24%
2949

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
57%7%12%18%4
1283
16th to endDay
54%7%15%17%4
1536
February1st to 15thDay
63%6%9%13%6%
1518
16th to endDay
63%5%12%10%6%
1485
March1st to 15thDay
57%8%15%15%2
1821
16th to endDay
55%7%18%15%3
2205
April1st to 15thDay
49%7%17%19%6%
2150
16th to endDay
52%5%14%18%6%1
2381
May1st to 15thDay
45%6%12%25%9%
2511
16th to endDay
51%8%12%19%8%
2620
June1st to 15thDay
50%8%14%19%6%
2763
16th to endDay
41%8%17%25%6%
2832
July1st to 15thDay
31%8%17%29%12%
2541
16th to endDay
27%6%16%31%16%1
2501
August1st to 15thDay
36%6%17%28%9%1
2504
16th to endDay
29%5%13%34%15%2
2416
September1st to 15thDay
37%414%26%15%1
2160
16th to endDay
35%412%32%12%1
1849
October1st to 15thDay
46%5%12%26%8%
1650
16th to endDay
48%5%19%21%4
1617
November1st to 15thDay
46%6%15%22%8%1
1441
16th to endDay
54%7%16%15%5%
1428
December1st to 15thDay
68%8%10%10%2
1260
16th to endDay
64%5%15%11%2
1269
January1st to 15thNight
52%7%17%18%4
2652
16th to endNight
52%9%15%15%5%1
2688
February1st to 15thNight
57%5%13%15%7%
2357
16th to endNight
57%6%12%16%6%
1989
March1st to 15thNight
49%6%16%21%6%
2136
16th to endNight
56%6%14%17%4
2019
April1st to 15thNight
40%7%14%23%12%1
1798
16th to endNight
47%7%13%18%11%2
1578
May1st to 15thNight
39%6%13%25%13%
1440
16th to endNight
48%6%12%21%11%
1498
June1st to 15thNight
38%6%16%25%11%1
1191
16th to endNight
31%6%20%30%9%
1124
July1st to 15thNight
24%8%18%34%12%1
1190
16th to endNight
20%6%16%34%18%3
1402
August1st to 15thNight
25%6%18%33%14%1
1432
16th to endNight
23%412%33%22%3
1784
September1st to 15thNight
32%5%10%28%19%3
1800
16th to endNight
33%5%10%30%18%1
1798
October1st to 15thNight
39%5%15%24%13%1
1980
16th to endNight
45%5%16%23%7%1
2244
November1st to 15thNight
47%6%15%18%10%2
2414
16th to endNight
54%6%16%16%5%
2529
December1st to 15thNight
65%6%12%12%3
2700
16th to endNight
57%6%14%15%5%
2949

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
10%6%18%38%24%1
65
16th to endDay
13%11%25%34%14%1
96
February1st to 15thDay
14%7%44%27%41
90
16th to endDay
11%9%34%32%8%3
81
March1st to 15thDay
18%13%38%22%41
111
16th to endDay
19%9%38%23%7%1
288
April1st to 15thDay
16%17%34%26%31
269
16th to endDay
25%7%24%29%12%
378
May1st to 15thDay
14%10%28%29%13%3
468
16th to endDay
21%9%21%24%15%7%
517
June1st to 15thDay
17%10%29%24%14%3
495
16th to endDay
13%10%28%29%16%2
495
July1st to 15thDay
9%423%34%22%4
475
16th to endDay
7%5%26%38%19%3
515
August1st to 15thDay
11%322%32%23%6%
493
16th to endDay
9%5%23%37%17%6%
355
September1st to 15thDay
18%9%28%27%13%2
315
16th to endDay
18%7%23%34%11%5%
156
October1st to 15thDay
31%5%34%14%13%1
90
16th to endDay
19%12%27%27%11%2
96
November1st to 15thDay
11%443%27%12%1
90
16th to endDay
16%10%33%25%14%
90
December1st to 15thDay
10%5%36%28%12%6%
90
16th to endDay
11%7%58%13%8%
68
January1st to 15thNight
10%12%38%30%7%1
900
16th to endNight
13%13%40%24%8%
960
February1st to 15thNight
12%9%32%30%12%2
773
16th to endNight
11%6%30%33%14%3
632
March1st to 15thNight
9%7%36%32%11%1
720
16th to endNight
16%7%34%30%10%
675
April1st to 15thNight
13%9%31%33%11%
539
16th to endNight
20%7%29%34%8%
540
May1st to 15thNight
15%5%29%34%12%2
540
16th to endNight
21%7%25%29%14%2
563
June1st to 15thNight
17%431%32%12%1
408
16th to endNight
11%5%26%38%17%
360
July1st to 15thNight
10%323%44%16%1
340
16th to endNight
5%325%47%17%1
550
August1st to 15thNight
9%220%42%21%2
539
16th to endNight
8%222%42%23%1
573
September1st to 15thNight
11%221%42%20%1
540
16th to endNight
12%5%27%40%11%1
531
October1st to 15thNight
17%7%28%32%12%2
660
16th to endNight
15%7%34%33%9%
836
November1st to 15thNight
16%9%36%25%9%1
875
16th to endNight
15%10%42%25%6%
900
December1st to 15thNight
15%6%36%28%10%2
900
16th to endNight
13%9%35%28%11%2
960
Page generated at 2017-09-17 10:05:41. Version ac04

Copyright 2017 A. Danko


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