Olds
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Olds clear sky chart from 2005-11-05 to 2018-10-27.

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
43%
16597
12%
51193
9%
16569
47%
16569
20%
35379

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
35%
970
10%
2910
7%
970
38%
970
15%
2211
January16th to endNight
36%
908
18%
2988
12%
908
44%
908
18%
2051
February1st to 15thNight
41%
760
13%
2634
13%
757
45%
757
16%
1840
February16th to endNight
42%
684
13%
2146
11%
684
46%
684
18%
1523
March1st to 15thNight
41%
780
15%
2298
11%
780
46%
780
20%
1637
March16th to endNight
36%
832
11%
2253
5%
831
40%
831
18%
1724
April1st to 15thNight
35%
675
11%
1845
5%
675
39%
675
18%
1391
April16th to endNight
37%
579
11%
1737
9%
579
40%
579
19%
1245
May1st to 15thNight
42%
434
10%
1497
9%
434
46%
434
21%
962
May16th to endNight
42%
406
5%
1421
2%
406
44%
406
18%
959
June1st to 15thNight
44%
390
0%
1365
0%
390
44%
390
15%
995
June16th to endNight
51%
390
0%
1365
0%
390
51%
390
19%
915
July1st to 15thNight
61%
370
1%
1295
0%
370
61%
370
22%
830
July16th to endNight
64%
408
7%
1375
6%
386
65%
386
28%
782
August1st to 15thNight
63%
410
9%
1554
13%
408
64%
408
23%
955
August16th to endNight
63%
621
16%
1863
15%
621
64%
621
34%
1096
September1st to 15thNight
55%
713
16%
1951
11%
713
57%
713
31%
1227
September16th to endNight
50%
776
18%
2145
11%
776
55%
776
33%
1362
October1st to 15thNight
43%
780
15%
2307
9%
780
48%
780
22%
1605
October16th to endNight
44%
816
17%
2652
13%
816
51%
816
24%
1713
November1st to 15thNight
36%
905
17%
2622
10%
905
42%
905
21%
1836
November16th to endNight
33%
975
13%
2925
7%
975
39%
975
18%
2105
December1st to 15thNight
37%
975
13%
2925
9%
975
40%
975
17%
2160
December16th to endNight
37%
1040
16%
3120
10%
1040
42%
1040
18%
2255

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
10%8%47%6%35%5%6%8%33%
52390
Night
8%9%47%6%35%5%6%8%33%
51346
TransparencyDay
47%7%17%20%7%
52043
Night
47%7%15%20%8%1
51198
SeeingDay
15%5%23%31%17%5%
7464
Night
12%427%36%16%2
16608

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
7%12%5%8%6%35%45%7%31%
1358
16th to endDay
6%11%6%11%6%35%5%7%7%29%
1599
February1st to 15thDay
8%12%5%9%8%45%46%7%28%
1558
16th to endDay
5%10%7%9%6%47%7%7%8%25%
1610
March1st to 15thDay
5%11%5%9%8%47%6%6%6%29%
1992
16th to endDay
9%14%6%9%6%45%5%6%6%24%
2316
April1st to 15thDay
11%14%6%8%6%45%5%6%7%23%
2433
16th to endDay
14%10%47%5%25%45%8%29%
2498
May1st to 15thDay
10%9%36%6%45%5%6%8%33%
2782
16th to endDay
19%6%26%6%35%5%5%8%28%
3042
June1st to 15thDay
17%7%36%6%46%6%6%8%25%
2925
16th to endDay
11%6%46%7%46%6%7%8%31%
2925
July1st to 15thDay
11%5%15%5%35%6%7%9%37%
2925
16th to endDay
8%324435%5%8%10%43%
3060
August1st to 15thDay
12%425%425%6%6%9%40%
2649
16th to endDay
10%314435%6%7%7%45%
2691
September1st to 15thDay
14%7%245%23446%44%
2337
16th to endDay
11%6%26%5%35%45%8%41%
2145
October1st to 15thDay
14%10%36%5%35%5%6%7%31%
1980
16th to endDay
7%7%48%6%35%46%8%35%
1828
November1st to 15thDay
7%13%5%9%7%35%5%6%6%29%
1551
16th to endDay
6%11%5%9%6%35%5%5%6%33%
1365
December1st to 15thDay
6%11%6%11%8%46%5%5%6%27%
1365
16th to endDay
311%5%12%8%46%6%5%8%27%
1456
January1st to 15thNight
5%11%6%10%9%47%5%6%7%24%
2910
16th to endNight
5%12%5%8%6%46%5%6%8%30%
2988
February1st to 15thNight
7%10%5%10%7%45%45%7%30%
2625
16th to endNight
412%6%8%7%48%5%5%6%30%
2146
March1st to 15thNight
5%9%48%7%46%6%7%10%29%
2298
16th to endNight
6%13%6%9%8%36%6%6%7%24%
2253
April1st to 15thNight
10%12%5%8%7%46%5%5%7%26%
1845
16th to endNight
13%10%37%6%35%5%5%6%31%
1737
May1st to 15thNight
12%7%45%5%26%6%6%9%34%
1496
16th to endNight
18%7%25%5%246%5%8%33%
1421
June1st to 15thNight
16%7%46%446%7%6%9%25%
1365
16th to endNight
12%6%36%6%446%6%8%33%
1365
July1st to 15thNight
7%5%26%6%46%7%7%9%36%
1365
16th to endNight
7%413435%5%7%10%45%
1460
August1st to 15thNight
8%426%6%35%5%7%8%40%
1562
16th to endNight
7%5%24425%6%5%8%47%
1863
September1st to 15thNight
13%5%2442345%7%44%
1951
16th to endNight
12%5%3442436%8%44%
2145
October1st to 15thNight
12%8%37%6%45%45%7%34%
2307
16th to endNight
7%9%36%5%35%5%7%9%37%
2652
November1st to 15thNight
6%10%48%7%35%5%6%7%34%
2622
16th to endNight
5%11%6%10%7%45%45%8%30%
2925
December1st to 15thNight
412%6%10%7%46%5%5%6%29%
2925
16th to endNight
312%5%10%9%46%5%5%8%28%
3120

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
50%5%14%20%6%1
1358
16th to endDay
51%7%13%15%9%3
1599
February1st to 15thDay
52%6%14%17%7%1
1558
16th to endDay
52%7%13%17%6%
1610
March1st to 15thDay
52%6%15%16%7%
1992
16th to endDay
57%6%13%16%5%
2317
April1st to 15thDay
57%6%15%14%5%
2433
16th to endDay
51%5%14%19%7%1
2498
May1st to 15thDay
45%5%16%21%9%
2782
16th to endDay
50%7%17%18%6%
3047
June1st to 15thDay
53%7%14%18%4
2925
16th to endDay
47%9%17%21%4
2925
July1st to 15thDay
39%8%24%21%4
2766
16th to endDay
33%9%23%25%7%
2883
August1st to 15thDay
37%8%25%23%5%
2632
16th to endDay
32%8%22%26%8%1
2691
September1st to 15thDay
40%5%19%21%11%2
2337
16th to endDay
40%5%14%26%10%2
2145
October1st to 15thDay
49%7%15%20%7%
1980
16th to endDay
44%6%13%25%9%
1828
November1st to 15thDay
53%7%12%17%7%1
1551
16th to endDay
49%6%15%18%7%1
1365
December1st to 15thDay
56%5%12%17%6%
1365
16th to endDay
52%6%13%16%9%1
1456
January1st to 15thNight
56%7%13%14%5%2
2910
16th to endNight
48%6%12%18%10%3
2988
February1st to 15thNight
51%6%12%19%8%1
2636
16th to endNight
52%5%11%18%11%1
2146
March1st to 15thNight
47%8%16%19%7%
2298
16th to endNight
55%6%12%18%5%1
2256
April1st to 15thNight
54%7%13%16%8%
1845
16th to endNight
51%5%13%21%6%1
1737
May1st to 15thNight
42%7%16%21%11%
1497
16th to endNight
47%7%17%19%7%1
1421
June1st to 15thNight
51%9%14%17%5%
1365
16th to endNight
45%8%17%20%6%
1365
July1st to 15thNight
39%10%19%25%4
1295
16th to endNight
31%9%22%27%9%
1375
August1st to 15thNight
37%9%22%23%6%
1554
16th to endNight
31%6%21%27%10%2
1863
September1st to 15thNight
36%5%17%23%12%3
1951
16th to endNight
37%5%17%24%11%3
2145
October1st to 15thNight
47%6%14%22%8%1
2307
16th to endNight
41%7%17%24%9%
2652
November1st to 15thNight
46%7%12%21%10%1
2622
16th to endNight
50%7%15%16%7%2
2925
December1st to 15thNight
54%6%12%20%5%1
2925
16th to endNight
51%6%11%20%8%1
3120

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
11%5%23%27%20%12%
90
16th to endDay
12%125%31%18%11%
96
February1st to 15thDay
19%419%36%14%8%
100
16th to endDay
10%224%38%19%4
191
March1st to 15thDay
12%5%35%30%10%5%
330
16th to endDay
16%434%30%11%2
352
April1st to 15thDay
19%9%27%27%13%2
329
16th to endDay
23%7%25%25%14%3
318
May1st to 15thDay
11%9%23%30%19%5%
455
16th to endDay
19%417%33%21%4
597
June1st to 15thDay
19%5%25%32%13%3
570
16th to endDay
11%5%23%34%18%6%
570
July1st to 15thDay
14%319%33%23%5%
550
16th to endDay
9%421%33%21%10%
569
August1st to 15thDay
14%317%33%20%11%
359
16th to endDay
11%321%36%20%6%
396
September1st to 15thDay
24%424%25%17%5%
375
16th to endDay
18%8%22%29%14%7%
375
October1st to 15thDay
23%6%26%26%12%5%
255
16th to endDay
12%6%23%35%17%4
178
November1st to 15thDay
18%326%33%14%4
133
16th to endDay
11%6%31%32%10%8%
90
December1st to 15thDay
12%5%33%21%18%8%
90
16th to endDay
7%432%33%20%2
96
January1st to 15thNight
12%6%30%34%13%1
975
16th to endNight
10%6%33%34%12%2
908
February1st to 15thNight
10%7%26%36%17%2
764
16th to endNight
8%427%36%18%3
684
March1st to 15thNight
9%331%36%15%3
780
16th to endNight
12%428%38%13%2
832
April1st to 15thNight
16%7%26%32%14%1
675
16th to endNight
18%6%25%36%12%1
579
May1st to 15thNight
15%5%29%32%17%
435
16th to endNight
22%421%34%16%
407
June1st to 15thNight
20%420%35%16%2
390
16th to endNight
14%419%36%22%1
390
July1st to 15thNight
11%215%43%26%
370
16th to endNight
9%117%44%24%1
408
August1st to 15thNight
10%29%39%35%2
410
16th to endNight
9%315%41%28%
621
September1st to 15thNight
17%217%37%21%3
713
16th to endNight
15%224%35%17%3
776
October1st to 15thNight
17%226%35%16%2
780
16th to endNight
10%431%39%12%
816
November1st to 15thNight
12%7%33%31%12%2
905
16th to endNight
9%5%37%32%11%2
975
December1st to 15thNight
12%5%28%35%15%2
975
16th to endNight
9%333%35%14%3
1040
Page generated at 2018-10-28 06:41:04. Version ac04

Copyright 2018 A. Danko


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