Dana-Jowsey Lakes Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dana-Jowsey Lakes Provincial Park clear sky chart from 2005-11-06 to 2026-08-15.

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	16% 12% 4 10% 5% 5% 5% 4 5% 6% 28%	144494
	Night	14% 15% 5% 12% 6% 5% 5% 3 5% 5% 25%	137666
Transparency	Day	56% 5% 11% 19% 8% 1	147922
	Night	61% 5% 9% 17% 7% 1	142314
Seeing	Day	25% 15% 32% 20% 7% 2	17742
	Night	24% 12% 31% 24% 8% 1	26756

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	10% 20% 10% 19% 7% 7% 6% 5% 4 4 9%	4094
	11th to 20th	Day	6% 16% 9% 19% 9% 6% 6% 4 6% 4 14%	4238
	21st to end	Day	5% 14% 7% 16% 8% 9% 9% 5% 6% 4 15%	5156
February	1st to 10th	Day	8% 14% 6% 13% 9% 8% 9% 4 6% 6% 19%	1886
	11th to 20th	Day	9% 20% 5% 11% 7% 7% 5% 5% 6% 7% 18%	1843
	21st to end	Day	9% 18% 6% 12% 8% 7% 7% 4 5% 5% 20%	1646
March	1st to 10th	Day	13% 18% 4 10% 7% 5% 5% 4 5% 6% 23%	4759
	11th to 20th	Day	15% 18% 6% 12% 8% 6% 4 3 4 5% 20%	5090
	21st to end	Day	14% 18% 5% 12% 5% 5% 5% 2 4 5% 24%	5586
April	1st to 10th	Day	19% 17% 6% 12% 4 3 3 3 4 6% 23%	2534
	11th to 20th	Day	19% 15% 4 9% 5% 4 3 3 4 5% 28%	2702
	21st to end	Day	20% 13% 4 8% 4 4 3 3 4 5% 32%	2730
May	1st to 10th	Day	15% 15% 4 9% 5% 5% 4 3 4 5% 30%	7777
	11th to 20th	Day	16% 10% 4 8% 5% 5% 5% 3 6% 7% 33%	8332
	21st to end	Day	17% 9% 3 6% 4 4 4 3 5% 7% 40%	9716
June	1st to 10th	Day	20% 9% 3 6% 4 5% 5% 4 6% 7% 31%	3150
	11th to 20th	Day	17% 8% 3 6% 5% 4 4 3 5% 8% 35%	3150
	21st to end	Day	20% 9% 2 7% 5% 5% 4 4 5% 7% 30%	3150
July	1st to 10th	Day	13% 6% 2 6% 4 5% 5% 4 8% 10% 36%	8879
	11th to 20th	Day	15% 6% 2 6% 5% 4 5% 4 7% 9% 37%	8880
	21st to end	Day	18% 7% 2 6% 4 4 5% 4 6% 8% 35%	9390
August	1st to 10th	Day	13% 6% 3 6% 5% 5% 5% 4 7% 9% 37%	4401
	11th to 20th	Day	18% 7% 3 7% 4 4 4 3 6% 7% 38%	4226
	21st to end	Day	17% 6% 2 7% 4 4 4 4 6% 9% 37%	4675
September	1st to 10th	Day	20% 6% 2 8% 5% 5% 4 4 5% 8% 33%	2438
	11th to 20th	Day	22% 10% 3 7% 4 4 3 3 5% 6% 33%	2200
	21st to end	Day	23% 11% 3 7% 5% 3 4 2 4 6% 33%	2200
October	1st to 10th	Day	22% 14% 4 7% 4 4 3 3 5% 5% 29%	2030
	11th to 20th	Day	25% 21% 5% 7% 4 4 3 3 3 4 20%	2000
	21st to end	Day	23% 25% 7% 10% 5% 3 3 3 3 4 15%	1995
November	1st to 10th	Day	20% 21% 6% 11% 4 4 4 2 4 4 18%	1701
	11th to 20th	Day	19% 24% 7% 15% 7% 5% 3 3 3 3 11%	1680
	21st to end	Day	19% 26% 6% 16% 7% 5% 4 2 3 3 9%	1666
December	1st to 10th	Day	13% 18% 10% 25% 11% 4 4 3 2 3 7%	2350
	11th to 20th	Day	12% 18% 6% 16% 8% 7% 5% 3 3 4 18%	2691
	21st to end	Day	19% 22% 9% 15% 7% 3 3 4 5% 4 10%	3553
January	1st to 10th	Night	8% 17% 10% 19% 10% 9% 6% 3 4 3 10%	8831
	11th to 20th	Night	8% 17% 8% 19% 10% 6% 6% 6% 5% 4 11%	8675
	21st to end	Night	5% 13% 8% 16% 9% 7% 8% 5% 7% 5% 17%	9058
February	1st to 10th	Night	8% 13% 5% 12% 11% 7% 7% 5% 6% 6% 19%	2732
	11th to 20th	Night	9% 17% 6% 14% 8% 6% 5% 4 5% 6% 20%	2663
	21st to end	Night	10% 17% 6% 14% 7% 7% 6% 4 5% 5% 19%	2158
March	1st to 10th	Night	17% 16% 5% 12% 5% 4 5% 3 4 4 25%	5300
	11th to 20th	Night	16% 20% 6% 14% 7% 4 3 2 3 4 21%	5089
	21st to end	Night	14% 15% 6% 12% 6% 5% 5% 3 4 6% 23%	5588
April	1st to 10th	Night	19% 15% 5% 10% 5% 5% 4 3 4 5% 25%	2102
	11th to 20th	Night	19% 13% 4 10% 4 5% 3 3 5% 5% 29%	1867
	21st to end	Night	19% 12% 4 8% 4 4 3 3 5% 7% 32%	1890
May	1st to 10th	Night	14% 13% 4 9% 5% 5% 4 3 5% 5% 33%	5121
	11th to 20th	Night	14% 10% 3 6% 4 4 4 4 6% 6% 38%	4531
	21st to end	Night	15% 9% 2 6% 4 4 3 3 5% 6% 42%	4492
June	1st to 10th	Night	22% 9% 3 6% 4 4 4 3 4 7% 34%	1470
	11th to 20th	Night	15% 8% 2 8% 5% 4 4 3 6% 7% 37%	1470
	21st to end	Night	19% 9% 2 6% 4 4 3 4 5% 9% 35%	1470
July	1st to 10th	Night	14% 6% 2 6% 4 4 4 3 6% 8% 43%	4110
	11th to 20th	Night	15% 7% 2 6% 4 3 5% 4 6% 9% 39%	4110
	21st to end	Night	18% 6% 2 6% 4 4 4 3 6% 8% 40%	4717
August	1st to 10th	Night	9% 7% 3 7% 5% 5% 6% 5% 6% 7% 40%	2968
	11th to 20th	Night	17% 9% 2 6% 4 3 4 3 5% 7% 40%	2911
	21st to end	Night	15% 7% 2 6% 3 3 3 3 4 5% 48%	3223
September	1st to 10th	Night	19% 8% 3 5% 4 4 3 3 5% 6% 39%	1940
	11th to 20th	Night	21% 11% 2 5% 3 3 3 2 4 6% 40%	2200
	21st to end	Night	20% 12% 2 6% 4 3 4 2 4 5% 37%	2200
October	1st to 10th	Night	20% 13% 2 7% 5% 4 4 3 5% 7% 31%	2369
	11th to 20th	Night	26% 18% 4 7% 4 4 4 3 4 4 21%	2400
	21st to end	Night	21% 23% 5% 8% 4 4 4 3 4 5% 20%	2840
November	1st to 10th	Night	18% 19% 6% 13% 5% 4 4 3 4 4 18%	2817
	11th to 20th	Night	20% 19% 7% 14% 6% 5% 4 2 3 3 15%	2940
	21st to end	Night	18% 23% 8% 16% 7% 5% 4 3 3 3 10%	2951
December	1st to 10th	Night	10% 25% 10% 20% 10% 7% 3 2 2 3 7%	5060
	11th to 20th	Night	10% 18% 7% 16% 10% 8% 6% 4 4 4 13%	5736
	21st to end	Night	20% 22% 6% 14% 7% 5% 4 3 4 4 12%	7667

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	80% 3 6% 8% 2 1	4095
	11th to 20th	Day	71% 3 6% 13% 7%	4265
	21st to end	Day	71% 3 5% 17% 5%	5156
February	1st to 10th	Day	65% 6% 8% 15% 6%	1886
	11th to 20th	Day	64% 5% 9% 13% 8%	1852
	21st to end	Day	66% 4 5% 15% 8% 1	1646
March	1st to 10th	Day	62% 5% 8% 13% 10% 2	4762
	11th to 20th	Day	67% 4 10% 11% 7%	5090
	21st to end	Day	64% 4 7% 15% 10% 1	5586
April	1st to 10th	Day	64% 5% 6% 16% 8% 1	2534
	11th to 20th	Day	57% 5% 7% 21% 10% 1	2702
	21st to end	Day	55% 4 9% 16% 13% 2	2730
May	1st to 10th	Day	56% 5% 7% 15% 16% 2	7786
	11th to 20th	Day	49% 6% 11% 19% 11% 3	8336
	21st to end	Day	45% 5% 9% 25% 14% 2	9717
June	1st to 10th	Day	50% 6% 11% 20% 12% 1	3150
	11th to 20th	Day	47% 7% 11% 22% 13%	3150
	21st to end	Day	52% 7% 11% 19% 10%	3150
July	1st to 10th	Day	41% 5% 15% 27% 12%	8806
	11th to 20th	Day	42% 5% 21% 22% 9%	8799
	21st to end	Day	48% 5% 14% 27% 6%	9182
August	1st to 10th	Day	42% 7% 16% 27% 8%	4386
	11th to 20th	Day	46% 6% 15% 27% 6%	4265
	21st to end	Day	44% 5% 15% 27% 6% 2	4674
September	1st to 10th	Day	49% 7% 15% 20% 8%	2438
	11th to 20th	Day	51% 7% 15% 21% 6%	2200
	21st to end	Day	54% 5% 11% 22% 8%	2200
October	1st to 10th	Day	55% 5% 13% 21% 6%	3303
	11th to 20th	Day	61% 3 11% 20% 5%	3240
	21st to end	Day	72% 3 11% 9% 5%	3195
November	1st to 10th	Day	70% 6% 9% 10% 5%	1701
	11th to 20th	Day	79% 4 7% 7% 3	1680
	21st to end	Day	82% 4 7% 6% 1	1666
December	1st to 10th	Day	85% 3 5% 4 3	2350
	11th to 20th	Day	71% 4 12% 11% 2	2691
	21st to end	Day	79% 3 4 13% 3	3553
January	1st to 10th	Night	79% 4 6% 7% 2	8831
	11th to 20th	Night	76% 3 6% 11% 5%	8723
	21st to end	Night	67% 4 6% 17% 6%	9058
February	1st to 10th	Night	63% 5% 11% 13% 7%	2732
	11th to 20th	Night	64% 5% 10% 15% 6%	2665
	21st to end	Night	66% 5% 8% 14% 7% 1	2158
March	1st to 10th	Night	64% 4 8% 13% 9% 3	5310
	11th to 20th	Night	69% 4 6% 13% 7% 1	5090
	21st to end	Night	62% 5% 7% 14% 11% 2	5588
April	1st to 10th	Night	61% 5% 8% 15% 11% 1	2102
	11th to 20th	Night	56% 5% 8% 18% 11% 2	1867
	21st to end	Night	53% 4 9% 17% 15% 2	1890
May	1st to 10th	Night	51% 5% 7% 20% 13% 2	5128
	11th to 20th	Night	45% 6% 12% 24% 11% 2	4532
	21st to end	Night	41% 5% 11% 25% 16% 2	4493
June	1st to 10th	Night	49% 6% 9% 20% 13% 3	1470
	11th to 20th	Night	46% 5% 11% 22% 16% 1	1470
	21st to end	Night	46% 7% 11% 23% 12% 1	1470
July	1st to 10th	Night	40% 4 12% 31% 13%	4075
	11th to 20th	Night	42% 4 15% 30% 8%	4068
	21st to end	Night	43% 4 17% 29% 6%	4611
August	1st to 10th	Night	42% 6% 15% 32% 5%	2959
	11th to 20th	Night	44% 6% 14% 31% 5%	2938
	21st to end	Night	38% 5% 13% 33% 11% 1	3223
September	1st to 10th	Night	46% 6% 16% 24% 8%	1940
	11th to 20th	Night	46% 6% 17% 25% 5%	2200
	21st to end	Night	49% 6% 15% 23% 7%	2200
October	1st to 10th	Night	52% 5% 11% 25% 7%	3876
	11th to 20th	Night	61% 5% 10% 19% 6%	3899
	21st to end	Night	64% 5% 15% 12% 4	4578
November	1st to 10th	Night	69% 5% 11% 12% 3	2817
	11th to 20th	Night	75% 4 9% 9% 3	2940
	21st to end	Night	81% 5% 7% 6% 1	2951
December	1st to 10th	Night	85% 3 5% 5% 2	5060
	11th to 20th	Night	75% 4 6% 10% 4	5735
	21st to end	Night	76% 3 6% 11% 4	7667

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	23% 18% 37% 15% 6% 1	220
	11th to 20th	Day	19% 18% 34% 23% 5% 2	248
	21st to end	Day	22% 13% 36% 23% 5% 1	363
February	1st to 10th	Day	22% 22% 36% 16% 4 1	330
	11th to 20th	Day	20% 20% 41% 15% 3 2	330
	21st to end	Day	24% 28% 34% 12% 2	273
March	1st to 10th	Day	23% 19% 40% 15% 3	408
	11th to 20th	Day	27% 19% 34% 16% 5% 1	540
	21st to end	Day	26% 20% 33% 15% 5% 1	594
April	1st to 10th	Day	25% 19% 32% 17% 6% 1	540
	11th to 20th	Day	30% 19% 28% 14% 7% 2	532
	21st to end	Day	31% 17% 27% 16% 7% 2	540
May	1st to 10th	Day	24% 13% 36% 17% 8% 2	543
	11th to 20th	Day	22% 17% 33% 19% 7% 2	600
	21st to end	Day	24% 16% 32% 20% 8% 1	844
June	1st to 10th	Day	23% 14% 36% 20% 7% 1	780
	11th to 20th	Day	25% 16% 30% 21% 7% 1	780
	21st to end	Day	26% 12% 26% 24% 10% 2	780
July	1st to 10th	Day	18% 12% 33% 28% 7% 3	771
	11th to 20th	Day	19% 14% 29% 27% 10% 2	768
	21st to end	Day	19% 9% 33% 25% 11% 3	849
August	1st to 10th	Day	18% 10% 32% 27% 10% 4	591
	11th to 20th	Day	19% 8% 29% 25% 15% 5%	535
	21st to end	Day	23% 10% 28% 23% 11% 5%	583
September	1st to 10th	Day	25% 11% 29% 22% 10% 2	530
	11th to 20th	Day	26% 9% 30% 22% 9% 2	530
	21st to end	Day	29% 14% 26% 22% 8% 1	530
October	1st to 10th	Day	29% 16% 29% 19% 5% 2	530
	11th to 20th	Day	35% 18% 29% 14% 2 1	530
	21st to end	Day	31% 22% 29% 16% 3 1	378
November	1st to 10th	Day	39% 15% 31% 13% 2	250
	11th to 20th	Day	34% 23% 30% 10% 2	220
	21st to end	Day	39% 23% 26% 9% 3	220
December	1st to 10th	Day	23% 16% 40% 15% 6% 1	220
	11th to 20th	Day	27% 18% 39% 12% 3 1	220
	21st to end	Day	31% 17% 32% 14% 5% 1	242
January	1st to 10th	Night	22% 13% 38% 20% 5% 1	1050
	11th to 20th	Night	22% 14% 31% 24% 8% 1	1050
	21st to end	Night	17% 13% 31% 28% 9% 1	1155
February	1st to 10th	Night	14% 15% 37% 25% 7% 1	842
	11th to 20th	Night	18% 15% 35% 24% 7% 1	823
	21st to end	Night	19% 16% 36% 23% 5%	692
March	1st to 10th	Night	22% 15% 36% 21% 6% 1	840
	11th to 20th	Night	24% 18% 33% 20% 5% 1	840
	21st to end	Night	20% 14% 37% 21% 7% 1	924
April	1st to 10th	Night	27% 16% 29% 21% 5% 1	747
	11th to 20th	Night	27% 15% 25% 24% 8% 1	623
	21st to end	Night	24% 13% 29% 25% 8% 1	630
May	1st to 10th	Night	21% 9% 33% 29% 8%	583
	11th to 20th	Night	23% 10% 32% 28% 5% 2	414
	21st to end	Night	18% 11% 36% 29% 6%	455
June	1st to 10th	Night	28% 8% 25% 32% 6%	420
	11th to 20th	Night	18% 9% 33% 31% 10%	420
	21st to end	Night	20% 9% 26% 33% 11% 1	420
July	1st to 10th	Night	17% 9% 30% 33% 10% 1	410
	11th to 20th	Night	17% 6% 31% 36% 11%	408
	21st to end	Night	16% 5% 30% 34% 13% 1	546
August	1st to 10th	Night	16% 6% 28% 34% 14% 2	627
	11th to 20th	Night	18% 6% 23% 33% 19% 2	606
	21st to end	Night	21% 7% 28% 26% 16% 2	660
September	1st to 10th	Night	24% 8% 27% 26% 13% 2	725
	11th to 20th	Night	28% 7% 27% 26% 12% 1	800
	21st to end	Night	28% 9% 26% 25% 11% 2	800
October	1st to 10th	Night	27% 11% 28% 26% 8%	800
	11th to 20th	Night	35% 13% 29% 17% 5% 1	800
	21st to end	Night	35% 12% 26% 21% 5% 1	880
November	1st to 10th	Night	31% 15% 30% 19% 4 1	820
	11th to 20th	Night	32% 16% 29% 18% 5%	840
	21st to end	Night	31% 16% 33% 15% 4	851
December	1st to 10th	Night	24% 17% 33% 20% 6%	1050
	11th to 20th	Night	25% 14% 35% 19% 6%	1050
	21st to end	Night	29% 14% 30% 19% 6% 1	1155

Page generated at 2026-08-12 03:37:20. Version ac07

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