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 2025-02-25.

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% 13% 4 9% 5% 4 4 3 5% 6% 29%	109509
	Night	16% 15% 5% 10% 5% 4 4 3 4 5% 27%	109147
Transparency	Day	55% 5% 10% 20% 9% 1	113131
	Night	58% 5% 10% 18% 9% 1	113689
Seeing	Day	25% 16% 30% 19% 8% 2	15129
	Night	24% 14% 29% 24% 9% 1	24041

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	12% 18% 7% 17% 8% 5% 3 2 4 4 21%	3597
	11th to 20th	Day	10% 22% 10% 16% 8% 7% 5% 3 3 4 13%	3644
	21st to end	Day	13% 20% 9% 16% 7% 6% 4 2 3 4 16%	4466
February	1st to 10th	Day	12% 21% 7% 16% 8% 5% 3 2 3 3 19%	1800
	11th to 20th	Day	14% 15% 8% 14% 5% 5% 4 3 4 6% 22%	1753
	21st to end	Day	16% 19% 7% 12% 6% 5% 4 4 4 3 20%	1472
March	1st to 10th	Day	18% 18% 4 9% 5% 4 3 3 5% 6% 25%	3414
	11th to 20th	Day	10% 18% 8% 13% 6% 5% 4 3 5% 5% 23%	3480
	21st to end	Day	13% 13% 5% 8% 5% 4 4 3 4 6% 37%	3815
April	1st to 10th	Day	21% 16% 3 8% 5% 4 4 3 5% 5% 26%	2278
	11th to 20th	Day	23% 13% 3 6% 4 3 4 3 4 4 33%	2331
	21st to end	Day	22% 13% 4 8% 4 3 3 2 3 5% 33%	2470
May	1st to 10th	Day	20% 9% 4 7% 4 5% 5% 4 5% 7% 31%	4252
	11th to 20th	Day	15% 9% 3 7% 4 4 4 4 6% 9% 36%	4398
	21st to end	Day	19% 7% 2 5% 4 4 4 4 5% 7% 40%	4837
June	1st to 10th	Day	22% 10% 3 6% 5% 4 5% 4 5% 7% 30%	2660
	11th to 20th	Day	17% 6% 2 7% 5% 4 5% 4 6% 8% 35%	2807
	21st to end	Day	21% 9% 3 6% 4 4 5% 4 5% 7% 33%	2850
July	1st to 10th	Day	16% 6% 2 7% 5% 5% 6% 4 7% 9% 33%	4760
	11th to 20th	Day	15% 6% 2 6% 5% 5% 5% 4 6% 8% 39%	4450
	21st to end	Day	11% 6% 2 6% 5% 4 4 4 5% 7% 46%	4724
August	1st to 10th	Day	14% 8% 3 8% 5% 5% 6% 5% 6% 8% 32%	4104
	11th to 20th	Day	18% 7% 2 7% 4 4 5% 4 7% 8% 33%	4044
	21st to end	Day	11% 5% 2 6% 5% 5% 5% 5% 6% 10% 41%	4354
September	1st to 10th	Day	18% 7% 2 6% 4 4 5% 4 6% 7% 37%	2280
	11th to 20th	Day	16% 6% 2 5% 4 4 4 3 5% 6% 43%	2214
	21st to end	Day	21% 9% 2 7% 4 4 4 3 5% 6% 34%	2024
October	1st to 10th	Day	22% 8% 3 8% 5% 5% 4 3 5% 6% 32%	1900
	11th to 20th	Day	28% 12% 3 8% 4 4 4 3 4 7% 21%	1900
	21st to end	Day	31% 15% 4 8% 4 3 3 3 4 5% 20%	2090
November	1st to 10th	Day	20% 15% 4 7% 5% 4 4 3 5% 6% 27%	1595
	11th to 20th	Day	19% 19% 6% 11% 4 5% 4 3 4 5% 21%	1600
	21st to end	Day	22% 24% 7% 10% 5% 3 3 3 4 4 15%	1600
December	1st to 10th	Day	17% 24% 9% 12% 6% 4 4 3 4 5% 12%	2600
	11th to 20th	Day	19% 25% 6% 12% 6% 3 2 2 4 3 18%	2986
	21st to end	Day	21% 22% 8% 14% 5% 3 3 2 3 4 15%	3960
January	1st to 10th	Night	13% 19% 9% 16% 7% 5% 4 3 4 4 16%	6349
	11th to 20th	Night	11% 19% 8% 22% 8% 5% 4 3 4 5% 11%	6226
	21st to end	Night	12% 21% 10% 15% 6% 8% 4 3 3 4 14%	6490
February	1st to 10th	Night	12% 19% 6% 15% 7% 5% 4 3 4 5% 19%	2600
	11th to 20th	Night	12% 16% 7% 14% 7% 4 5% 3 3 5% 23%	2533
	21st to end	Night	15% 19% 6% 13% 6% 6% 4 3 4 5% 20%	2076
March	1st to 10th	Night	16% 15% 5% 9% 5% 4 4 3 4 6% 28%	3422
	11th to 20th	Night	12% 20% 7% 9% 5% 4 4 3 5% 6% 26%	3479
	21st to end	Night	14% 10% 6% 7% 7% 5% 5% 3 6% 5% 33%	3817
April	1st to 10th	Night	22% 15% 3 6% 4 4 3 3 4 6% 29%	1901
	11th to 20th	Night	19% 12% 3 7% 4 4 3 3 4 6% 35%	1815
	21st to end	Night	20% 11% 4 8% 4 5% 5% 3 5% 5% 31%	1710
May	1st to 10th	Night	18% 8% 3 6% 5% 5% 5% 3 5% 7% 36%	2687
	11th to 20th	Night	15% 9% 2 7% 4 5% 4 3 5% 7% 39%	2495
	21st to end	Night	13% 8% 3 5% 4 4 4 3 6% 8% 42%	2738
June	1st to 10th	Night	16% 11% 3 6% 6% 5% 4 4 5% 6% 35%	1520
	11th to 20th	Night	15% 6% 3 5% 4 4 3 4 6% 7% 43%	1367
	21st to end	Night	18% 7% 3 6% 5% 5% 4 4 6% 8% 35%	1330
July	1st to 10th	Night	11% 7% 3 8% 5% 5% 4 4 4 7% 42%	2210
	11th to 20th	Night	19% 7% 2 4 3 3 3 3 5% 6% 45%	2506
	21st to end	Night	12% 6% 2 5% 3 3 4 3 5% 8% 49%	2826
August	1st to 10th	Night	12% 5% 2 5% 3 4 5% 4 5% 8% 46%	2825
	11th to 20th	Night	18% 8% 3 5% 4 4 4 3 5% 7% 40%	2785
	21st to end	Night	15% 5% 2 5% 3 3 4 3 5% 7% 48%	3270
September	1st to 10th	Night	13% 6% 2 6% 5% 3 5% 4 5% 6% 45%	1900
	11th to 20th	Night	15% 6% 2 5% 4 3 4 3 5% 7% 47%	1963
	21st to end	Night	20% 8% 2 5% 4 4 3 3 4 6% 41%	2156
October	1st to 10th	Night	20% 9% 3 6% 4 5% 4 2 5% 6% 36%	2280
	11th to 20th	Night	26% 11% 3 8% 4 4 4 3 4 6% 26%	2280
	21st to end	Night	27% 15% 4 8% 5% 4 3 3 4 4 23%	2508
November	1st to 10th	Night	22% 15% 3 7% 4 3 4 3 4 6% 29%	2699
	11th to 20th	Night	18% 18% 4 8% 5% 4 4 3 5% 6% 25%	2800
	21st to end	Night	23% 20% 5% 10% 6% 4 4 3 4 5% 16%	2800
December	1st to 10th	Night	20% 25% 7% 13% 5% 4 4 3 4 4 10%	4580
	11th to 20th	Night	17% 24% 8% 15% 5% 4 3 2 3 4 15%	5208
	21st to end	Night	22% 22% 7% 14% 6% 4 3 2 3 4 15%	6996

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	69% 3 6% 15% 7%	3598
	11th to 20th	Day	78% 2 5% 9% 6% 1	3674
	21st to end	Day	75% 3 5% 9% 8% 1	4466
February	1st to 10th	Day	72% 3 6% 13% 6% 1	1800
	11th to 20th	Day	66% 3 9% 12% 8% 2	1762
	21st to end	Day	69% 3 8% 11% 8%	1472
March	1st to 10th	Day	60% 5% 12% 10% 11% 1	3417
	11th to 20th	Day	63% 4 10% 14% 8% 1	3480
	21st to end	Day	49% 5% 8% 21% 14% 3	3815
April	1st to 10th	Day	59% 4 9% 18% 8% 2	2278
	11th to 20th	Day	55% 4 7% 22% 12% 1	2331
	21st to end	Day	56% 3 8% 17% 13% 3	2470
May	1st to 10th	Day	51% 6% 9% 22% 11% 2	4264
	11th to 20th	Day	44% 6% 12% 27% 10% 1	4402
	21st to end	Day	44% 5% 13% 18% 16% 4	4837
June	1st to 10th	Day	54% 5% 9% 19% 12%	2660
	11th to 20th	Day	45% 6% 11% 23% 14% 1	2807
	21st to end	Day	50% 6% 12% 20% 10% 2	2850
July	1st to 10th	Day	46% 6% 14% 23% 10% 1	4686
	11th to 20th	Day	42% 6% 14% 29% 9%	4374
	21st to end	Day	37% 5% 11% 31% 14%	4573
August	1st to 10th	Day	49% 6% 12% 24% 7% 1	4091
	11th to 20th	Day	47% 6% 14% 26% 7%	4083
	21st to end	Day	37% 6% 13% 33% 10%	4354
September	1st to 10th	Day	44% 6% 13% 25% 11% 1	2280
	11th to 20th	Day	40% 6% 13% 28% 13%	2214
	21st to end	Day	51% 6% 10% 25% 9%	2024
October	1st to 10th	Day	51% 6% 12% 23% 8% 1	3160
	11th to 20th	Day	56% 5% 10% 21% 8%	3140
	21st to end	Day	65% 4 11% 16% 4	3428
November	1st to 10th	Day	57% 5% 13% 19% 5%	1595
	11th to 20th	Day	66% 6% 9% 12% 6% 1	1600
	21st to end	Day	75% 4 9% 9% 3 1	1600
December	1st to 10th	Day	76% 4 9% 8% 2	2600
	11th to 20th	Day	73% 3 5% 12% 7%	2986
	21st to end	Day	75% 3 4 12% 6%	3960
January	1st to 10th	Night	72% 4 6% 13% 5%	6349
	11th to 20th	Night	77% 4 6% 6% 6% 1	6271
	21st to end	Night	76% 4 5% 7% 7% 1	6490
February	1st to 10th	Night	68% 4 8% 13% 6% 1	2600
	11th to 20th	Night	65% 3 7% 17% 7% 1	2535
	21st to end	Night	68% 4 7% 14% 7% 1	2076
March	1st to 10th	Night	58% 3 12% 14% 11% 2	3432
	11th to 20th	Night	59% 4 13% 15% 7% 1	3480
	21st to end	Night	50% 6% 7% 23% 12% 2	3817
April	1st to 10th	Night	58% 4 8% 18% 11% 2	1901
	11th to 20th	Night	51% 4 7% 22% 15% 1	1815
	21st to end	Night	55% 5% 7% 16% 14% 2	1710
May	1st to 10th	Night	46% 6% 12% 23% 11% 1	2694
	11th to 20th	Night	44% 6% 10% 27% 12% 1	2496
	21st to end	Night	41% 5% 11% 24% 16% 2	2739
June	1st to 10th	Night	48% 6% 11% 20% 12% 2	1520
	11th to 20th	Night	38% 5% 13% 25% 18%	1367
	21st to end	Night	47% 6% 15% 21% 10% 1	1330
July	1st to 10th	Night	41% 6% 14% 24% 14% 1	2175
	11th to 20th	Night	41% 5% 12% 32% 10% 1	2459
	21st to end	Night	34% 6% 11% 33% 16% 1	2736
August	1st to 10th	Night	36% 6% 17% 26% 15% 1	2814
	11th to 20th	Night	43% 6% 16% 25% 9% 1	2812
	21st to end	Night	35% 5% 14% 33% 12% 1	3270
September	1st to 10th	Night	38% 8% 14% 27% 12% 1	1900
	11th to 20th	Night	36% 6% 15% 29% 13%	1963
	21st to end	Night	45% 5% 13% 27% 10%	2156
October	1st to 10th	Night	41% 5% 10% 28% 16%	3800
	11th to 20th	Night	52% 5% 14% 19% 10%	3779
	21st to end	Night	60% 4 16% 13% 5%	4120
November	1st to 10th	Night	58% 4 13% 19% 6%	2699
	11th to 20th	Night	61% 5% 11% 16% 7% 1	2800
	21st to end	Night	71% 4 9% 11% 4	2800
December	1st to 10th	Night	77% 5% 9% 7% 2	4580
	11th to 20th	Night	75% 3 6% 9% 7%	5208
	21st to end	Night	76% 3 5% 10% 6%	6996

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	18% 27% 36% 15% 5% 1	200
	11th to 20th	Day	27% 18% 35% 15% 3 1	217
	21st to end	Day	26% 19% 35% 14% 6%	330
February	1st to 10th	Day	30% 27% 33% 6% 2 1	300
	11th to 20th	Day	29% 27% 36% 7% 1	300
	21st to end	Day	35% 23% 35% 8%	260
March	1st to 10th	Day	23% 22% 36% 17% 1 1	460
	11th to 20th	Day	23% 25% 32% 17% 4 1	460
	21st to end	Day	30% 17% 31% 17% 5% 1	506
April	1st to 10th	Day	28% 20% 30% 16% 6% 1	460
	11th to 20th	Day	37% 18% 21% 14% 8% 3	452
	21st to end	Day	32% 16% 30% 14% 7% 2	460
May	1st to 10th	Day	28% 13% 30% 20% 5% 3	463
	11th to 20th	Day	24% 16% 29% 19% 10% 3	487
	21st to end	Day	23% 17% 28% 21% 9% 3	529
June	1st to 10th	Day	25% 12% 33% 23% 5% 1	490
	11th to 20th	Day	19% 15% 32% 23% 10% 2	637
	21st to end	Day	25% 13% 33% 19% 8% 2	680
July	1st to 10th	Day	14% 11% 32% 30% 11% 2	671
	11th to 20th	Day	17% 11% 29% 26% 13% 4	493
	21st to end	Day	15% 10% 34% 26% 12% 3	532
August	1st to 10th	Day	17% 9% 27% 31% 10% 6%	486
	11th to 20th	Day	18% 6% 25% 29% 15% 7%	479
	21st to end	Day	20% 10% 28% 24% 13% 5%	539
September	1st to 10th	Day	20% 11% 29% 21% 14% 4	490
	11th to 20th	Day	17% 10% 23% 23% 19% 8%	490
	21st to end	Day	24% 14% 23% 24% 12% 2	490
October	1st to 10th	Day	27% 16% 25% 17% 12% 4	490
	11th to 20th	Day	30% 18% 32% 14% 4 1	490
	21st to end	Day	39% 16% 28% 14% 3	539
November	1st to 10th	Day	36% 18% 29% 13% 3	229
	11th to 20th	Day	33% 20% 35% 10% 4	200
	21st to end	Day	31% 25% 37% 7% 1 1	200
December	1st to 10th	Day	35% 16% 34% 12% 3 1	200
	11th to 20th	Day	39% 26% 22% 12% 2 1	200
	21st to end	Day	28% 25% 27% 15% 3 1	220
January	1st to 10th	Night	27% 20% 32% 17% 4	800
	11th to 20th	Night	30% 17% 31% 18% 4	800
	21st to end	Night	20% 14% 35% 22% 8% 1	880
February	1st to 10th	Night	23% 21% 36% 16% 3	800
	11th to 20th	Night	22% 20% 35% 19% 4	783
	21st to end	Night	26% 22% 29% 20% 3	647
March	1st to 10th	Night	22% 20% 34% 19% 4	760
	11th to 20th	Night	20% 19% 34% 20% 4 1	760
	21st to end	Night	20% 16% 33% 23% 8%	836
April	1st to 10th	Night	28% 13% 33% 21% 5%	760
	11th to 20th	Night	26% 14% 29% 21% 8% 1	691
	21st to end	Night	26% 11% 28% 23% 11%	570
May	1st to 10th	Night	24% 7% 28% 29% 11% 1	489
	11th to 20th	Night	19% 9% 33% 29% 9%	374
	21st to end	Night	13% 10% 33% 34% 9%	411
June	1st to 10th	Night	20% 8% 31% 32% 9% 1	380
	11th to 20th	Night	19% 8% 25% 36% 12%	380
	21st to end	Night	21% 8% 22% 36% 13% 1	380
July	1st to 10th	Night	12% 5% 25% 40% 17% 1	370
	11th to 20th	Night	16% 5% 25% 35% 18%	368
	21st to end	Night	10% 4 23% 42% 18% 1	467
August	1st to 10th	Night	16% 4 19% 37% 23% 2	567
	11th to 20th	Night	14% 6% 17% 37% 22% 3	564
	21st to end	Night	18% 6% 25% 30% 18% 3	708
September	1st to 10th	Night	17% 6% 26% 31% 18% 2	760
	11th to 20th	Night	17% 6% 24% 27% 22% 4	760
	21st to end	Night	25% 8% 20% 29% 16% 2	760
October	1st to 10th	Night	24% 12% 26% 24% 12% 1	760
	11th to 20th	Night	30% 14% 28% 19% 8% 1	760
	21st to end	Night	36% 14% 29% 18% 3	836
November	1st to 10th	Night	31% 13% 28% 22% 6% 1	780
	11th to 20th	Night	28% 19% 29% 18% 6%	800
	21st to end	Night	33% 18% 27% 18% 4	800
December	1st to 10th	Night	32% 18% 30% 14% 4	800
	11th to 20th	Night	27% 22% 33% 14% 4 1	800
	21st to end	Night	34% 17% 29% 17% 3	880

Page generated at 2025-02-22 06:51:37. Version ac07

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