Nordegg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nordegg clear sky chart from 2005-11-06 to 2026-07-01.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	8% 10% 4 10% 6% 5% 6% 4 6% 8% 32%	143151
	Night	6% 10% 4 10% 6% 5% 5% 4 6% 8% 34%	137902
Transparency	Day	47% 5% 14% 22% 10% 1	142853
	Night	46% 5% 15% 22% 11% 1	137783
Seeing	Day	18% 18% 30% 22% 10% 2	18009
	Night	13% 13% 33% 27% 12% 1	26347

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	1 8% 5% 12% 7% 6% 6% 5% 7% 10% 32%	4125
	11th to 20th	Day	2 8% 3 8% 6% 7% 6% 5% 6% 8% 41%	4298
	21st to end	Day	1 7% 4 13% 7% 6% 6% 5% 6% 9% 36%	5186
February	1st to 10th	Day	3 10% 6% 11% 8% 7% 6% 5% 7% 7% 29%	1680
	11th to 20th	Day	3 13% 5% 14% 6% 6% 5% 5% 6% 8% 30%	1729
	21st to end	Day	1 9% 5% 14% 9% 6% 8% 4 7% 6% 29%	1730
March	1st to 10th	Day	1 7% 4 13% 7% 6% 5% 4 7% 11% 35%	4618
	11th to 20th	Day	2 10% 5% 11% 6% 5% 5% 4 7% 8% 36%	4878
	21st to end	Day	6% 17% 7% 16% 6% 5% 5% 4 5% 7% 22%	5935
April	1st to 10th	Day	5% 19% 5% 11% 8% 6% 6% 5% 6% 7% 21%	2520
	11th to 20th	Day	8% 18% 6% 12% 7% 5% 4 5% 5% 7% 23%	2698
	21st to end	Day	9% 16% 6% 13% 6% 6% 6% 3 5% 6% 24%	2782
May	1st to 10th	Day	10% 13% 4 10% 6% 6% 5% 4 6% 8% 29%	8210
	11th to 20th	Day	11% 13% 4 11% 7% 7% 6% 5% 7% 8% 22%	8755
	21st to end	Day	13% 11% 4 10% 6% 6% 6% 4 6% 7% 27%	9649
June	1st to 10th	Day	18% 10% 4 8% 5% 6% 6% 4 7% 6% 25%	3158
	11th to 20th	Day	21% 11% 4 9% 6% 5% 6% 5% 6% 7% 19%	3360
	21st to end	Day	13% 8% 3 9% 7% 6% 6% 5% 7% 8% 30%	3360
July	1st to 10th	Day	9% 7% 2 7% 5% 5% 5% 4 6% 8% 41%	7224
	11th to 20th	Day	12% 6% 2 7% 5% 5% 6% 5% 7% 8% 36%	6780
	21st to end	Day	11% 7% 3 7% 5% 5% 6% 5% 8% 8% 36%	7113
August	1st to 10th	Day	14% 7% 2 6% 5% 5% 5% 4 6% 8% 37%	4541
	11th to 20th	Day	12% 7% 3 8% 5% 6% 6% 5% 7% 8% 33%	4389
	21st to end	Day	12% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	4664
September	1st to 10th	Day	13% 10% 3 6% 5% 4 4 4 5% 7% 39%	2415
	11th to 20th	Day	13% 9% 3 6% 5% 3 4 3 6% 8% 39%	2267
	21st to end	Day	11% 10% 3 7% 5% 4 5% 4 6% 8% 39%	2200
October	1st to 10th	Day	7% 11% 3 8% 4 5% 5% 4 6% 8% 39%	3432
	11th to 20th	Day	7% 10% 4 9% 4 5% 5% 4 6% 9% 36%	2932
	21st to end	Day	6% 10% 4 9% 6% 5% 5% 4 6% 7% 38%	3200
November	1st to 10th	Day	5% 13% 6% 12% 7% 4 4 4 7% 7% 31%	1736
	11th to 20th	Day	3 11% 4 9% 5% 6% 5% 4 7% 9% 36%	1470
	21st to end	Day	3 10% 5% 10% 7% 5% 5% 5% 7% 10% 32%	1470
December	1st to 10th	Day	6% 12% 6% 13% 7% 6% 7% 4 6% 7% 26%	2360
	11th to 20th	Day	2 8% 5% 12% 6% 6% 6% 5% 7% 8% 35%	2712
	21st to end	Day	1 10% 5% 11% 5% 5% 6% 4 5% 7% 41%	3575
January	1st to 10th	Night	1 9% 6% 16% 7% 7% 6% 5% 7% 8% 28%	8768
	11th to 20th	Night	1 8% 4 11% 7% 6% 5% 4 7% 8% 39%	8659
	21st to end	Night	2 8% 5% 15% 7% 6% 5% 4 6% 8% 34%	8994
February	1st to 10th	Night	3 12% 4 13% 9% 6% 6% 4 5% 7% 30%	2940
	11th to 20th	Night	3 12% 5% 12% 8% 6% 6% 4 7% 8% 29%	2774
	21st to end	Night	1 8% 5% 13% 9% 7% 6% 5% 5% 6% 34%	2076
March	1st to 10th	Night	2 8% 3 11% 7% 7% 6% 5% 6% 10% 35%	5496
	11th to 20th	Night	3 8% 5% 11% 5% 5% 5% 5% 8% 10% 34%	5340
	21st to end	Night	6% 17% 8% 15% 5% 4 4 3 5% 7% 26%	5279
April	1st to 10th	Night	5% 14% 5% 10% 6% 6% 6% 4 6% 8% 30%	2100
	11th to 20th	Night	7% 16% 5% 11% 7% 5% 4 3 5% 7% 30%	1872
	21st to end	Night	8% 16% 4 9% 5% 4 6% 5% 6% 7% 30%	1836
May	1st to 10th	Night	12% 15% 4 8% 4 4 4 4 6% 7% 34%	4707
	11th to 20th	Night	11% 14% 4 10% 6% 5% 6% 5% 7% 7% 25%	4105
	21st to end	Night	10% 9% 3 7% 4 4 5% 4 7% 9% 37%	4522
June	1st to 10th	Night	19% 9% 3 7% 5% 5% 4 4 5% 7% 33%	1457
	11th to 20th	Night	19% 9% 3 7% 5% 5% 5% 6% 7% 7% 27%	1260
	21st to end	Night	12% 7% 3 8% 5% 4 4 5% 7% 8% 38%	1260
July	1st to 10th	Night	10% 7% 3 7% 4 4 4 4 6% 8% 43%	2720
	11th to 20th	Night	11% 6% 2 5% 4 4 5% 4 7% 9% 43%	3180
	21st to end	Night	12% 8% 3 5% 4 4 4 3 4 7% 45%	3728
August	1st to 10th	Night	14% 7% 2 7% 3 4 4 3 6% 8% 41%	2609
	11th to 20th	Night	13% 9% 3 6% 4 4 4 5% 7% 10% 35%	2661
	21st to end	Night	14% 8% 2 6% 4 3 3 3 5% 8% 44%	3245
September	1st to 10th	Night	11% 7% 3 7% 4 3 5% 4 5% 7% 44%	1983
	11th to 20th	Night	14% 9% 3 6% 4 4 4 4 6% 7% 41%	2132
	21st to end	Night	9% 9% 3 6% 3 4 4 5% 7% 7% 43%	2200
October	1st to 10th	Night	7% 10% 4 7% 5% 5% 5% 5% 6% 8% 38%	3763
	11th to 20th	Night	7% 10% 3 9% 5% 4 4 4 7% 7% 39%	4216
	21st to end	Night	5% 12% 4 9% 5% 5% 4 4 5% 7% 42%	4600
November	1st to 10th	Night	4 14% 5% 12% 5% 4 5% 4 5% 7% 35%	2757
	11th to 20th	Night	3 11% 5% 9% 6% 6% 6% 5% 8% 9% 35%	3150
	21st to end	Night	3 11% 4 11% 8% 5% 5% 5% 6% 8% 32%	3150
December	1st to 10th	Night	3 11% 6% 11% 8% 7% 6% 5% 6% 7% 28%	5040
	11th to 20th	Night	1 10% 5% 13% 9% 8% 6% 5% 7% 8% 27%	5700
	21st to end	Night	1 12% 6% 12% 6% 6% 5% 4 6% 8% 34%	7623

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	43% 5% 14% 23% 13% 2	4125
	11th to 20th	Day	38% 4 16% 23% 16% 3	4319
	21st to end	Day	43% 4 19% 24% 10%	5187
February	1st to 10th	Day	51% 3 12% 17% 13% 4	1680
	11th to 20th	Day	52% 4 12% 19% 11% 2	1737
	21st to end	Day	52% 5% 12% 16% 14% 1	1730
March	1st to 10th	Day	41% 4 16% 19% 18% 2	4618
	11th to 20th	Day	40% 4 15% 24% 16% 1	4879
	21st to end	Day	60% 4 10% 18% 8% 1	5935
April	1st to 10th	Day	60% 4 13% 16% 6% 1	2520
	11th to 20th	Day	60% 4 11% 17% 7% 1	2698
	21st to end	Day	60% 4 10% 19% 6% 1	2782
May	1st to 10th	Day	52% 4 10% 24% 9%	8210
	11th to 20th	Day	55% 5% 11% 19% 8% 1	8759
	21st to end	Day	54% 5% 15% 18% 7%	9650
June	1st to 10th	Day	56% 4 12% 19% 8% 2	3158
	11th to 20th	Day	60% 5% 11% 15% 8% 1	3360
	21st to end	Day	48% 5% 16% 20% 10% 1	3360
July	1st to 10th	Day	36% 7% 14% 21% 18% 4	7145
	11th to 20th	Day	40% 8% 15% 24% 11% 2	6699
	21st to end	Day	40% 9% 15% 23% 12% 1	6913
August	1st to 10th	Day	41% 6% 14% 30% 8%	4524
	11th to 20th	Day	43% 8% 17% 23% 9% 1	4431
	21st to end	Day	40% 6% 17% 28% 8% 1	4663
September	1st to 10th	Day	45% 3 15% 24% 10% 2	2415
	11th to 20th	Day	43% 4 15% 26% 10% 2	2267
	21st to end	Day	44% 4 16% 22% 12% 3	2200
October	1st to 10th	Day	40% 7% 19% 26% 8% 1	3432
	11th to 20th	Day	44% 5% 16% 23% 10% 2	2932
	21st to end	Day	43% 5% 13% 30% 8% 1	3200
November	1st to 10th	Day	51% 4 15% 19% 11% 2	1736
	11th to 20th	Day	44% 4 18% 22% 12% 1	1470
	21st to end	Day	44% 4 19% 21% 9% 3	1470
December	1st to 10th	Day	55% 6% 16% 14% 7% 1	2360
	11th to 20th	Day	45% 4 19% 23% 8% 1	2714
	21st to end	Day	42% 4 10% 24% 16% 3	3575
January	1st to 10th	Night	51% 5% 11% 19% 12% 2	8769
	11th to 20th	Night	41% 5% 16% 18% 16% 4	8700
	21st to end	Night	47% 4 20% 20% 8% 1	8994
February	1st to 10th	Night	53% 3 11% 18% 12% 2	2940
	11th to 20th	Night	50% 4 13% 18% 13% 2	2776
	21st to end	Night	49% 3 9% 24% 13% 2	2076
March	1st to 10th	Night	44% 3 18% 19% 14% 1	5496
	11th to 20th	Night	43% 4 16% 22% 15% 1	5340
	21st to end	Night	57% 4 8% 19% 12%	5279
April	1st to 10th	Night	52% 4 13% 21% 10% 1	2100
	11th to 20th	Night	55% 3 14% 19% 9% 1	1872
	21st to end	Night	51% 5% 12% 25% 7% 1	1836
May	1st to 10th	Night	49% 3 12% 27% 7% 1	4704
	11th to 20th	Night	53% 5% 10% 22% 9%	4105
	21st to end	Night	42% 4 18% 29% 7% 1	4526
June	1st to 10th	Night	50% 3 14% 22% 9% 2	1457
	11th to 20th	Night	52% 5% 16% 20% 7%	1260
	21st to end	Night	42% 5% 18% 27% 8% 1	1260
July	1st to 10th	Night	35% 7% 19% 21% 13% 4	2690
	11th to 20th	Night	33% 8% 21% 26% 9% 3	3138
	21st to end	Night	37% 5% 21% 25% 11% 1	3623
August	1st to 10th	Night	39% 5% 16% 35% 5%	2601
	11th to 20th	Night	40% 7% 22% 24% 6%	2685
	21st to end	Night	39% 4 17% 31% 7% 1	3245
September	1st to 10th	Night	39% 3 17% 28% 10% 3	1983
	11th to 20th	Night	42% 4 15% 27% 10% 3	2132
	21st to end	Night	38% 4 18% 26% 12% 2	2200
October	1st to 10th	Night	40% 7% 18% 24% 9% 1	3763
	11th to 20th	Night	41% 4 14% 29% 10% 1	4216
	21st to end	Night	41% 5% 14% 29% 10%	4600
November	1st to 10th	Night	49% 3 12% 22% 12% 1	2757
	11th to 20th	Night	45% 4 17% 21% 12% 1	3150
	21st to end	Night	48% 4 15% 21% 10% 3	3150
December	1st to 10th	Night	51% 7% 16% 17% 8% 2	5040
	11th to 20th	Night	53% 5% 16% 16% 9% 1	5697
	21st to end	Night	47% 3 13% 23% 12% 2	7623

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	7% 16% 31% 31% 10% 5%	220
	11th to 20th	Day	11% 16% 38% 24% 8% 3	220
	21st to end	Day	14% 19% 43% 18% 5% 2	242
February	1st to 10th	Day	15% 18% 38% 20% 6% 3	220
	11th to 20th	Day	7% 21% 37% 26% 9%	277
	21st to end	Day	11% 24% 33% 22% 9% 2	446
March	1st to 10th	Day	14% 23% 36% 18% 7% 2	540
	11th to 20th	Day	15% 21% 36% 19% 6% 3	540
	21st to end	Day	19% 25% 32% 17% 6% 2	594
April	1st to 10th	Day	22% 21% 31% 18% 6% 1	540
	11th to 20th	Day	20% 24% 27% 21% 7% 1	532
	21st to end	Day	20% 21% 29% 20% 9% 2	540
May	1st to 10th	Day	26% 18% 26% 23% 8%	545
	11th to 20th	Day	18% 13% 29% 24% 14% 2	775
	21st to end	Day	25% 13% 25% 22% 12% 2	844
June	1st to 10th	Day	23% 17% 29% 21% 9% 1	788
	11th to 20th	Day	26% 16% 26% 21% 9% 2	990
	21st to end	Day	17% 12% 27% 25% 16% 3	990
July	1st to 10th	Day	17% 11% 29% 28% 12% 2	913
	11th to 20th	Day	16% 12% 27% 27% 16% 2	718
	21st to end	Day	15% 13% 28% 27% 14% 4	684
August	1st to 10th	Day	17% 14% 25% 30% 10% 4	527
	11th to 20th	Day	15% 17% 31% 26% 9% 3	517
	21st to end	Day	17% 15% 30% 24% 11% 4	583
September	1st to 10th	Day	21% 19% 26% 23% 10% 2	530
	11th to 20th	Day	20% 16% 28% 23% 10% 3	530
	21st to end	Day	21% 24% 30% 17% 7% 2	530
October	1st to 10th	Day	20% 17% 30% 18% 12% 3	506
	11th to 20th	Day	17% 18% 36% 17% 10% 2	330
	21st to end	Day	21% 18% 34% 17% 9% 1	363
November	1st to 10th	Day	19% 27% 28% 19% 5% 2	313
	11th to 20th	Day	16% 22% 34% 21% 6% 1	220
	21st to end	Day	8% 27% 29% 25% 9% 3	220
December	1st to 10th	Day	12% 25% 33% 18% 9% 4	220
	11th to 20th	Day	12% 21% 38% 21% 8%	220
	21st to end	Day	8% 18% 36% 26% 10% 1	242
January	1st to 10th	Night	11% 16% 38% 27% 7% 1	1050
	11th to 20th	Night	11% 19% 41% 22% 6% 1	1008
	21st to end	Night	13% 20% 39% 20% 7% 1	924
February	1st to 10th	Night	11% 17% 33% 26% 11% 2	840
	11th to 20th	Night	11% 14% 38% 27% 9%	824
	21st to end	Night	5% 13% 40% 27% 13% 2	692
March	1st to 10th	Night	8% 16% 37% 27% 11% 2	840
	11th to 20th	Night	9% 15% 38% 27% 9% 1	840
	21st to end	Night	11% 14% 34% 29% 11% 2	924
April	1st to 10th	Night	14% 15% 29% 28% 13% 1	840
	11th to 20th	Night	17% 15% 32% 26% 9%	624
	21st to end	Night	20% 14% 28% 27% 10%	576
May	1st to 10th	Night	22% 9% 26% 28% 13% 1	420
	11th to 20th	Night	15% 8% 25% 36% 15% 1	414
	21st to end	Night	22% 5% 24% 29% 19% 1	455
June	1st to 10th	Night	24% 9% 27% 23% 15% 2	420
	11th to 20th	Night	22% 7% 22% 31% 16% 1	420
	21st to end	Night	14% 6% 23% 32% 23% 2	420
July	1st to 10th	Night	15% 4 22% 37% 21%	390
	11th to 20th	Night	16% 5% 27% 31% 21%	388
	21st to end	Night	13% 6% 17% 37% 25% 3	438
August	1st to 10th	Night	19% 2 16% 31% 28% 4	398
	11th to 20th	Night	14% 6% 18% 37% 24% 1	441
	21st to end	Night	14% 8% 21% 37% 19% 1	660
September	1st to 10th	Night	16% 8% 24% 34% 17% 1	783
	11th to 20th	Night	19% 7% 21% 32% 19% 2	800
	21st to end	Night	15% 12% 33% 27% 12% 1	800
October	1st to 10th	Night	17% 10% 28% 31% 12% 1	800
	11th to 20th	Night	16% 13% 32% 30% 8% 1	800
	21st to end	Night	16% 14% 37% 26% 6% 2	880
November	1st to 10th	Night	15% 17% 36% 24% 8% 1	883
	11th to 20th	Night	12% 20% 41% 21% 5%	1050
	21st to end	Night	10% 19% 38% 24% 8% 1	1050
December	1st to 10th	Night	11% 18% 41% 20% 9% 1	1050
	11th to 20th	Night	8% 18% 40% 26% 8%	1050
	21st to end	Night	8% 16% 43% 23% 8% 1	1155

Page generated at 2026-06-28 00:10:50. Version ac07

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