Oxtongue Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oxtongue Lake 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	17% 12% 4 9% 5% 4 4 3 5% 6% 30%	139164
	Night	16% 14% 5% 10% 5% 4 4 3 4 6% 28%	133185
Transparency	Day	55% 5% 10% 20% 10% 1	142740
	Night	58% 4 9% 18% 10% 1	137698
Seeing	Day	25% 16% 30% 19% 7% 2	16940
	Night	24% 14% 29% 24% 9% 1	25658

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	13% 17% 6% 15% 8% 5% 4 3 4 5% 21%	4661
	11th to 20th	Day	9% 25% 11% 17% 7% 7% 4 2 3 3 11%	4752
	21st to end	Day	10% 17% 8% 20% 7% 7% 5% 3 3 4 17%	5780
February	1st to 10th	Day	12% 20% 7% 16% 8% 5% 3 3 3 3 19%	1890
	11th to 20th	Day	14% 15% 8% 15% 5% 5% 4 3 4 6% 21%	1843
	21st to end	Day	15% 20% 7% 12% 6% 5% 4 4 4 3 20%	1582
March	1st to 10th	Day	19% 16% 4 12% 6% 4 3 3 4 5% 24%	5009
	11th to 20th	Day	13% 15% 6% 11% 6% 5% 5% 3 6% 7% 24%	5090
	21st to end	Day	17% 18% 5% 8% 4 3 3 3 3 4 32%	5586
April	1st to 10th	Day	20% 16% 3 8% 5% 4 4 3 5% 5% 26%	2518
	11th to 20th	Day	24% 13% 3 6% 4 3 4 3 4 4 33%	2579
	21st to end	Day	22% 13% 4 8% 4 3 3 2 4 5% 33%	2730
May	1st to 10th	Day	17% 10% 3 7% 5% 5% 5% 4 5% 8% 30%	7896
	11th to 20th	Day	18% 9% 3 7% 4 4 4 4 5% 7% 35%	8221
	21st to end	Day	20% 9% 3 6% 4 4 4 4 5% 6% 37%	9060
June	1st to 10th	Day	21% 9% 3 6% 5% 4 4 4 5% 6% 31%	2940
	11th to 20th	Day	17% 7% 2 7% 5% 4 5% 4 6% 8% 35%	3103
	21st to end	Day	20% 9% 2 6% 4 4 5% 4 6% 8% 32%	3150
July	1st to 10th	Day	17% 6% 2 6% 5% 5% 5% 4 6% 9% 35%	6820
	11th to 20th	Day	14% 5% 2 6% 4 5% 4 4 5% 7% 44%	6370
	21st to end	Day	9% 6% 2 5% 5% 4 4 4 5% 8% 48%	6794
August	1st to 10th	Day	14% 8% 3 8% 5% 5% 6% 5% 6% 8% 32%	4234
	11th to 20th	Day	18% 7% 2 7% 4 4 5% 5% 6% 8% 33%	4174
	21st to end	Day	11% 5% 2 6% 5% 5% 5% 5% 6% 10% 41%	4492
September	1st to 10th	Day	17% 7% 2 7% 4 4 5% 4 6% 7% 37%	2400
	11th to 20th	Day	15% 6% 2 5% 4 4 4 3 5% 7% 44%	2330
	21st to end	Day	22% 9% 2 7% 4 4 4 3 5% 6% 34%	2130
October	1st to 10th	Day	21% 7% 3 7% 5% 5% 4 3 5% 6% 34%	2000
	11th to 20th	Day	28% 12% 3 8% 4 5% 4 3 4 7% 22%	2000
	21st to end	Day	30% 15% 3 8% 4 3 3 3 4 5% 21%	2200
November	1st to 10th	Day	21% 16% 4 7% 5% 4 4 3 4 6% 27%	1676
	11th to 20th	Day	18% 20% 6% 11% 4 4 4 3 4 5% 21%	1680
	21st to end	Day	21% 25% 7% 10% 5% 3 3 3 4 4 15%	1680
December	1st to 10th	Day	16% 25% 9% 12% 6% 4 4 3 4 5% 13%	2680
	11th to 20th	Day	19% 25% 6% 12% 6% 3 2 2 4 3 18%	3066
	21st to end	Day	21% 22% 8% 14% 5% 3 3 2 3 4 15%	4048
January	1st to 10th	Night	13% 18% 10% 18% 7% 5% 4 3 4 4 15%	8234
	11th to 20th	Night	10% 21% 9% 22% 8% 5% 4 3 4 4 11%	8118
	21st to end	Night	9% 18% 10% 16% 8% 8% 5% 3 3 4 16%	8401
February	1st to 10th	Night	12% 19% 6% 14% 7% 5% 4 3 5% 5% 20%	2730
	11th to 20th	Night	12% 16% 8% 15% 7% 5% 5% 3 3 5% 23%	2663
	21st to end	Night	14% 19% 6% 13% 6% 6% 4 3 4 5% 19%	2223
March	1st to 10th	Night	17% 15% 5% 11% 5% 4 4 4 4 5% 27%	5047
	11th to 20th	Night	10% 16% 7% 10% 5% 5% 5% 4 6% 8% 25%	5089
	21st to end	Night	20% 12% 6% 7% 6% 4 4 3 5% 4 29%	5588
April	1st to 10th	Night	22% 15% 4 7% 4 3 3 3 4 6% 29%	2101
	11th to 20th	Night	19% 12% 3 7% 4 4 4 3 5% 6% 34%	2009
	21st to end	Night	19% 11% 4 8% 5% 5% 5% 3 4 5% 31%	1890
May	1st to 10th	Night	19% 9% 3 6% 4 5% 5% 3 5% 7% 34%	5001
	11th to 20th	Night	18% 8% 2 6% 4 4 3 3 5% 7% 41%	4639
	21st to end	Night	19% 8% 2 4 4 4 4 3 5% 7% 40%	5114
June	1st to 10th	Night	16% 11% 2 6% 5% 4 4 4 5% 6% 36%	1680
	11th to 20th	Night	16% 6% 3 5% 4 4 3 4 6% 7% 43%	1511
	21st to end	Night	17% 7% 3 6% 5% 4 5% 4 6% 8% 36%	1470
July	1st to 10th	Night	15% 6% 3 7% 4 4 4 4 5% 8% 39%	3160
	11th to 20th	Night	17% 6% 2 5% 3 3 3 3 5% 6% 46%	3586
	21st to end	Night	12% 6% 2 5% 3 3 4 3 4 7% 52%	4055
August	1st to 10th	Night	12% 5% 2 5% 3 4 5% 4 5% 8% 46%	2915
	11th to 20th	Night	18% 8% 3 5% 4 4 4 3 4 7% 40%	2875
	21st to end	Night	15% 5% 2 5% 3 3 3 3 5% 7% 48%	3373
September	1st to 10th	Night	13% 6% 2 6% 5% 3 5% 4 6% 6% 45%	2000
	11th to 20th	Night	14% 6% 2 5% 4 3 4 3 5% 7% 48%	2067
	21st to end	Night	20% 8% 2 5% 4 4 3 3 4 6% 41%	2270
October	1st to 10th	Night	19% 8% 3 6% 4 5% 4 2 5% 7% 38%	2400
	11th to 20th	Night	26% 11% 3 7% 4 4 4 3 4 6% 27%	2400
	21st to end	Night	27% 15% 4 8% 5% 4 3 3 4 4 24%	2640
November	1st to 10th	Night	22% 15% 4 8% 4 3 4 3 4 6% 28%	2838
	11th to 20th	Night	18% 18% 5% 8% 5% 4 4 3 5% 6% 25%	2940
	21st to end	Night	23% 21% 5% 10% 6% 5% 4 3 3 5% 16%	2940
December	1st to 10th	Night	19% 25% 7% 13% 6% 4 4 3 5% 4 11%	4720
	11th to 20th	Night	17% 24% 8% 15% 6% 4 3 2 3 4 15%	5348
	21st to end	Night	22% 22% 7% 14% 6% 4 3 2 3 4 15%	7150

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	67% 3 7% 15% 6% 1	4662
	11th to 20th	Day	81% 2 4 7% 6% 1	4782
	21st to end	Day	74% 3 4 10% 8% 1	5780
February	1st to 10th	Day	71% 3 6% 13% 6% 1	1890
	11th to 20th	Day	66% 3 9% 13% 8% 2	1852
	21st to end	Day	69% 3 8% 12% 8%	1582
March	1st to 10th	Day	63% 4 10% 8% 13% 1	5012
	11th to 20th	Day	61% 4 12% 15% 7% 2	5090
	21st to end	Day	57% 4 7% 18% 13% 2	5586
April	1st to 10th	Day	59% 4 8% 18% 9% 2	2518
	11th to 20th	Day	56% 4 7% 21% 12% 1	2579
	21st to end	Day	56% 3 7% 18% 12% 3	2730
May	1st to 10th	Day	51% 6% 9% 20% 9% 4	7905
	11th to 20th	Day	47% 5% 9% 24% 14% 1	8225
	21st to end	Day	48% 4 11% 21% 13% 2	9061
June	1st to 10th	Day	53% 5% 9% 19% 13%	2940
	11th to 20th	Day	45% 6% 11% 24% 13% 1	3103
	21st to end	Day	49% 7% 13% 21% 9% 1	3150
July	1st to 10th	Day	44% 6% 14% 25% 10% 1	6747
	11th to 20th	Day	39% 5% 12% 33% 11%	6294
	21st to end	Day	34% 5% 14% 34% 12%	6598
August	1st to 10th	Day	48% 6% 13% 25% 7% 1	4221
	11th to 20th	Day	47% 6% 14% 26% 7%	4213
	21st to end	Day	37% 6% 13% 34% 10%	4492
September	1st to 10th	Day	44% 5% 14% 24% 11% 1	2400
	11th to 20th	Day	39% 6% 13% 29% 13%	2330
	21st to end	Day	51% 5% 10% 25% 9%	2130
October	1st to 10th	Day	49% 6% 12% 23% 9% 1	3260
	11th to 20th	Day	56% 5% 10% 20% 8% 1	3240
	21st to end	Day	65% 4 11% 16% 4	3538
November	1st to 10th	Day	58% 5% 12% 19% 5%	1676
	11th to 20th	Day	67% 5% 9% 12% 6% 1	1680
	21st to end	Day	75% 4 9% 9% 3	1680
December	1st to 10th	Day	76% 4 9% 8% 2	2680
	11th to 20th	Day	73% 3 5% 12% 7%	3066
	21st to end	Day	75% 3 4 12% 6%	4048
January	1st to 10th	Night	73% 4 6% 12% 5%	8234
	11th to 20th	Night	78% 3 5% 6% 7% 1	8163
	21st to end	Night	73% 4 5% 9% 8% 1	8401
February	1st to 10th	Night	66% 4 8% 13% 7% 1	2730
	11th to 20th	Night	66% 3 7% 17% 7%	2665
	21st to end	Night	68% 4 7% 14% 7% 1	2223
March	1st to 10th	Night	60% 4 10% 12% 11% 4	5057
	11th to 20th	Night	57% 5% 14% 15% 7% 1	5090
	21st to end	Night	57% 5% 5% 19% 12% 2	5588
April	1st to 10th	Night	58% 3 8% 18% 10% 2	2101
	11th to 20th	Night	51% 5% 7% 22% 14% 1	2009
	21st to end	Night	55% 4 7% 18% 13% 2	1890
May	1st to 10th	Night	48% 5% 8% 24% 11% 3	5008
	11th to 20th	Night	43% 5% 9% 24% 16% 2	4640
	21st to end	Night	44% 4 10% 26% 15% 1	5115
June	1st to 10th	Night	48% 6% 11% 20% 14% 2	1680
	11th to 20th	Night	39% 5% 13% 26% 17%	1511
	21st to end	Night	46% 5% 15% 21% 11% 1	1470
July	1st to 10th	Night	43% 6% 14% 26% 11% 1	3125
	11th to 20th	Night	39% 5% 11% 33% 11% 1	3539
	21st to end	Night	33% 5% 10% 39% 14% 1	3936
August	1st to 10th	Night	35% 6% 17% 26% 15% 1	2904
	11th to 20th	Night	43% 6% 16% 25% 10% 1	2902
	21st to end	Night	35% 5% 14% 33% 12% 1	3373
September	1st to 10th	Night	37% 8% 15% 27% 12% 1	2000
	11th to 20th	Night	36% 6% 15% 30% 14%	2067
	21st to end	Night	46% 5% 12% 26% 11%	2270
October	1st to 10th	Night	40% 5% 10% 28% 16%	3920
	11th to 20th	Night	52% 5% 14% 19% 10%	3899
	21st to end	Night	60% 4 16% 14% 6%	4252
November	1st to 10th	Night	58% 4 13% 18% 6%	2838
	11th to 20th	Night	61% 5% 11% 16% 6% 1	2940
	21st to end	Night	72% 4 8% 11% 4	2940
December	1st to 10th	Night	76% 5% 9% 8% 2	4720
	11th to 20th	Night	74% 3 6% 10% 7%	5348
	21st to end	Night	76% 3 5% 10% 6%	7150

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	19% 26% 35% 14% 5% 1	220
	11th to 20th	Day	28% 20% 34% 14% 3 1	239
	21st to end	Day	25% 20% 36% 13% 6%	363
February	1st to 10th	Day	29% 25% 33% 9% 3 1	330
	11th to 20th	Day	28% 27% 37% 7% 1	330
	21st to end	Day	33% 22% 36% 9%	298
March	1st to 10th	Day	24% 24% 36% 15% 1 1	540
	11th to 20th	Day	26% 24% 30% 15% 3 1	540
	21st to end	Day	32% 18% 29% 16% 4 1	594
April	1st to 10th	Day	30% 21% 28% 15% 5% 1	540
	11th to 20th	Day	39% 17% 21% 14% 8% 2	532
	21st to end	Day	32% 16% 31% 14% 6% 1	540
May	1st to 10th	Day	28% 16% 30% 18% 5% 3	543
	11th to 20th	Day	24% 18% 28% 19% 9% 2	567
	21st to end	Day	25% 19% 28% 18% 8% 3	617
June	1st to 10th	Day	25% 13% 34% 22% 5% 1	570
	11th to 20th	Day	20% 16% 31% 23% 8% 2	733
	21st to end	Day	24% 13% 34% 20% 7% 2	780
July	1st to 10th	Day	14% 11% 33% 31% 10% 2	722
	11th to 20th	Day	17% 12% 29% 27% 12% 4	533
	21st to end	Day	14% 11% 35% 25% 12% 3	576
August	1st to 10th	Day	16% 8% 26% 33% 11% 6%	526
	11th to 20th	Day	18% 7% 25% 30% 14% 6%	519
	21st to end	Day	19% 10% 29% 24% 12% 5%	583
September	1st to 10th	Day	20% 12% 28% 21% 15% 4	530
	11th to 20th	Day	15% 9% 22% 24% 19% 9%	530
	21st to end	Day	24% 14% 24% 24% 12% 2	530
October	1st to 10th	Day	26% 15% 26% 18% 12% 3	530
	11th to 20th	Day	31% 18% 33% 14% 4 1	530
	21st to end	Day	38% 16% 28% 15% 3	583
November	1st to 10th	Day	38% 18% 28% 13% 3	250
	11th to 20th	Day	33% 20% 34% 9% 4	220
	21st to end	Day	33% 24% 35% 6% 1	220
December	1st to 10th	Day	34% 18% 32% 12% 3	220
	11th to 20th	Day	40% 25% 21% 12% 1	220
	21st to end	Day	30% 24% 27% 14% 3 1	242
January	1st to 10th	Night	27% 19% 33% 18% 4	840
	11th to 20th	Night	30% 18% 31% 17% 4	840
	21st to end	Night	20% 15% 35% 22% 8% 1	924
February	1st to 10th	Night	23% 21% 35% 18% 3	840
	11th to 20th	Night	22% 20% 35% 20% 4	823
	21st to end	Night	25% 23% 29% 21% 3	692
March	1st to 10th	Night	23% 20% 35% 19% 4	840
	11th to 20th	Night	22% 19% 35% 20% 4 1	840
	21st to end	Night	23% 15% 31% 23% 8%	924
April	1st to 10th	Night	28% 14% 32% 21% 5%	840
	11th to 20th	Night	26% 15% 29% 22% 8% 1	765
	21st to end	Night	26% 11% 29% 23% 10%	630
May	1st to 10th	Night	24% 9% 28% 29% 10% 1	541
	11th to 20th	Night	20% 10% 34% 27% 9%	414
	21st to end	Night	16% 10% 32% 33% 9%	455
June	1st to 10th	Night	21% 8% 29% 33% 9% 1	420
	11th to 20th	Night	19% 9% 26% 35% 11%	420
	21st to end	Night	20% 8% 23% 37% 12%	420
July	1st to 10th	Night	12% 5% 26% 41% 16% 1	390
	11th to 20th	Night	16% 6% 24% 36% 18%	388
	21st to end	Night	11% 5% 24% 42% 17% 1	492
August	1st to 10th	Night	15% 4 18% 38% 24% 2	597
	11th to 20th	Night	15% 6% 17% 38% 21% 3	594
	21st to end	Night	18% 6% 26% 30% 17% 3	745
September	1st to 10th	Night	17% 6% 26% 31% 19% 2	800
	11th to 20th	Night	17% 6% 24% 28% 22% 4	800
	21st to end	Night	25% 9% 20% 29% 16% 2	800
October	1st to 10th	Night	23% 12% 26% 25% 13% 1	800
	11th to 20th	Night	31% 14% 29% 19% 7% 1	800
	21st to end	Night	35% 13% 29% 19% 3	880
November	1st to 10th	Night	31% 13% 28% 21% 6%	820
	11th to 20th	Night	28% 19% 29% 18% 7%	840
	21st to end	Night	33% 18% 27% 18% 3	840
December	1st to 10th	Night	32% 18% 31% 15% 4	840
	11th to 20th	Night	27% 22% 33% 14% 4 1	840
	21st to end	Night	34% 18% 29% 16% 3	924

Page generated at 2026-06-28 02:10:44. Version ac07

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