Mew Lake Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mew Lake Campground clear sky chart from 2005-11-06 to 2024-11-04.

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 9% 5% 5% 4 3 5% 6% 30%	102160
	Night	15% 14% 5% 10% 6% 5% 4 3 4 6% 28%	96845
Transparency	Day	55% 5% 10% 20% 9% 1	105728
	Night	56% 5% 11% 18% 9% 1	101367
Seeing	Day	24% 18% 31% 18% 7% 2	14806
	Night	23% 16% 31% 21% 8% 1	23556

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% 20% 7% 18% 7% 4 3 2 4 4 15%	2517
	11th to 20th	Day	11% 14% 8% 21% 12% 6% 3 3 5% 4 13%	2520
	21st to end	Day	15% 21% 12% 14% 4 4 4 2 3 4 17%	3124
February	1st to 10th	Day	10% 18% 8% 15% 10% 6% 4 3 4 4 17%	1710
	11th to 20th	Day	10% 16% 8% 14% 8% 5% 5% 3 5% 6% 22%	1663
	21st to end	Day	15% 18% 5% 12% 8% 5% 5% 4 4 5% 19%	1451
March	1st to 10th	Day	14% 19% 5% 11% 5% 4 4 3 5% 5% 25%	3366
	11th to 20th	Day	9% 19% 8% 13% 6% 5% 4 3 4 5% 24%	3480
	21st to end	Day	11% 12% 5% 10% 5% 5% 3 2 4 5% 38%	3841
April	1st to 10th	Day	19% 17% 5% 8% 4 4 4 3 4 6% 26%	2280
	11th to 20th	Day	21% 12% 4 8% 4 4 3 3 4 4 33%	2312
	21st to end	Day	20% 14% 4 8% 4 3 3 3 3 5% 32%	2470
May	1st to 10th	Day	19% 10% 3 7% 5% 4 4 4 5% 6% 31%	4295
	11th to 20th	Day	15% 9% 3 8% 5% 4 4 4 5% 8% 36%	4398
	21st to end	Day	17% 7% 3 6% 4 4 4 3 5% 7% 39%	4837
June	1st to 10th	Day	20% 11% 3 6% 5% 4 5% 4 6% 7% 29%	2660
	11th to 20th	Day	15% 8% 3 6% 5% 5% 5% 5% 5% 8% 37%	2778
	21st to end	Day	19% 8% 2 7% 5% 5% 5% 4 5% 8% 31%	2850
July	1st to 10th	Day	16% 7% 2 7% 6% 6% 5% 4 7% 8% 32%	4711
	11th to 20th	Day	14% 7% 2 6% 5% 5% 5% 5% 6% 7% 38%	4440
	21st to end	Day	11% 7% 3 6% 4 4 4 4 5% 8% 44%	4785
August	1st to 10th	Day	15% 7% 3 8% 5% 6% 6% 4 6% 8% 31%	4104
	11th to 20th	Day	19% 8% 2 7% 5% 5% 5% 5% 7% 6% 33%	4044
	21st to end	Day	11% 6% 2 6% 5% 6% 5% 4 7% 9% 40%	4340
September	1st to 10th	Day	16% 8% 2 5% 4 4 5% 4 6% 7% 38%	2280
	11th to 20th	Day	16% 6% 3 6% 4 4 3 4 5% 6% 43%	2239
	21st to end	Day	20% 10% 3 7% 5% 4 5% 3 4 7% 33%	2009
October	1st to 10th	Day	20% 10% 4 7% 4 4 5% 3 4 6% 32%	1900
	11th to 20th	Day	23% 18% 4 8% 5% 5% 4 2 4 5% 21%	1900
	21st to end	Day	27% 17% 5% 9% 5% 4 3 2 4 4 18%	2064
November	1st to 10th	Day	15% 17% 4 8% 5% 4 4 3 5% 7% 27%	1554
	11th to 20th	Day	17% 19% 6% 14% 5% 4 4 2 4 5% 20%	1520
	21st to end	Day	19% 22% 9% 13% 5% 5% 4 3 4 3 13%	1520
December	1st to 10th	Day	17% 25% 8% 13% 6% 4 3 3 4 5% 13%	1520
	11th to 20th	Day	15% 22% 10% 13% 6% 5% 4 3 3 4 16%	1906
	21st to end	Day	20% 23% 8% 16% 7% 3 2 2 2 4 14%	2772
January	1st to 10th	Night	14% 21% 9% 17% 8% 6% 4 3 4 4 10%	4429
	11th to 20th	Night	9% 16% 6% 19% 13% 8% 5% 3 4 4 11%	4436
	21st to end	Night	14% 19% 10% 17% 6% 5% 5% 3 3 3 14%	4532
February	1st to 10th	Night	10% 18% 7% 13% 8% 7% 4 4 5% 6% 17%	2470
	11th to 20th	Night	9% 16% 8% 13% 7% 5% 4 4 5% 5% 24%	2403
	21st to end	Night	11% 18% 6% 13% 7% 6% 5% 3 5% 5% 20%	2003
March	1st to 10th	Night	15% 15% 5% 10% 5% 4 4 3 4 6% 28%	3470
	11th to 20th	Night	12% 19% 7% 12% 6% 4 4 3 4 5% 25%	3479
	21st to end	Night	10% 11% 6% 10% 7% 5% 5% 3 5% 6% 32%	3790
April	1st to 10th	Night	19% 16% 5% 7% 4 4 3 2 4 6% 29%	1900
	11th to 20th	Night	17% 12% 4 7% 4 4 3 3 4 5% 36%	1834
	21st to end	Night	20% 10% 4 8% 5% 4 4 3 4 5% 31%	1710
May	1st to 10th	Night	18% 10% 3 6% 4 4 4 4 6% 7% 35%	2646
	11th to 20th	Night	15% 10% 2 6% 4 4 4 3 5% 8% 37%	2495
	21st to end	Night	11% 9% 2 8% 4 5% 4 3 5% 7% 41%	2738
June	1st to 10th	Night	17% 10% 3 7% 5% 4 6% 4 5% 6% 34%	1520
	11th to 20th	Night	15% 6% 2 6% 4 3 5% 3 5% 8% 43%	1397
	21st to end	Night	16% 10% 3 7% 5% 4 4 4 6% 7% 35%	1330
July	1st to 10th	Night	12% 9% 2 8% 4 4 4 4 5% 6% 41%	2239
	11th to 20th	Night	16% 8% 3 6% 3 4 4 3 4 6% 43%	2520
	21st to end	Night	11% 7% 2 5% 4 3 4 4 5% 7% 47%	2765
August	1st to 10th	Night	12% 4 2 5% 4 4 4 5% 7% 8% 45%	2825
	11th to 20th	Night	17% 8% 2 6% 4 4 5% 3 4 5% 41%	2785
	21st to end	Night	14% 4 2 5% 4 4 4 3 6% 8% 47%	3283
September	1st to 10th	Night	12% 6% 2 6% 3 4 4 4 5% 7% 46%	1900
	11th to 20th	Night	14% 9% 2 5% 4 3 3 2 5% 7% 47%	1938
	21st to end	Night	18% 8% 3 7% 4 4 3 3 4 7% 39%	2171
October	1st to 10th	Night	19% 11% 3 6% 4 4 4 4 5% 6% 36%	2280
	11th to 20th	Night	22% 15% 3 8% 4 4 4 3 4 5% 26%	2280
	21st to end	Night	24% 17% 5% 9% 5% 4 3 3 4 5% 22%	2532
November	1st to 10th	Night	16% 16% 5% 9% 4 5% 4 3 5% 5% 29%	2593
	11th to 20th	Night	16% 17% 5% 10% 6% 5% 4 3 5% 6% 23%	2660
	21st to end	Night	17% 22% 6% 12% 7% 5% 4 3 4 5% 15%	2660
December	1st to 10th	Night	16% 25% 8% 15% 7% 4 3 2 4 3 12%	2660
	11th to 20th	Night	14% 23% 9% 13% 6% 5% 4 3 3 4 17%	3288
	21st to end	Night	20% 23% 8% 16% 7% 4 3 2 3 3 11%	4884

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	73% 3 9% 8% 6%	2518
	11th to 20th	Day	73% 6% 6% 10% 5% 1	2520
	21st to end	Day	74% 3 5% 10% 6% 1	3124
February	1st to 10th	Day	70% 4 6% 13% 6% 1	1710
	11th to 20th	Day	64% 4 10% 12% 9% 1	1672
	21st to end	Day	66% 5% 7% 12% 9% 1	1451
March	1st to 10th	Day	61% 4 12% 10% 12% 1	3369
	11th to 20th	Day	63% 4 10% 14% 8% 1	3480
	21st to end	Day	48% 4 9% 21% 15% 3	3841
April	1st to 10th	Day	60% 4 8% 17% 9% 2	2280
	11th to 20th	Day	55% 4 7% 22% 11% 2	2312
	21st to end	Day	56% 5% 7% 17% 13% 3	2470
May	1st to 10th	Day	52% 6% 9% 21% 11% 2	4307
	11th to 20th	Day	47% 6% 10% 27% 9% 1	4402
	21st to end	Day	45% 6% 12% 19% 15% 3	4837
June	1st to 10th	Day	53% 6% 10% 20% 10% 1	2660
	11th to 20th	Day	45% 6% 10% 23% 14% 2	2778
	21st to end	Day	51% 6% 12% 20% 10% 1	2850
July	1st to 10th	Day	46% 7% 14% 24% 9% 1	4638
	11th to 20th	Day	42% 7% 14% 28% 8% 1	4365
	21st to end	Day	37% 6% 11% 31% 14%	4632
August	1st to 10th	Day	48% 7% 13% 24% 7% 1	4091
	11th to 20th	Day	47% 7% 13% 26% 6% 1	4083
	21st to end	Day	39% 7% 12% 32% 11%	4340
September	1st to 10th	Day	44% 6% 12% 25% 12% 1	2280
	11th to 20th	Day	42% 5% 13% 27% 13%	2239
	21st to end	Day	52% 6% 10% 23% 9%	2009
October	1st to 10th	Day	52% 6% 11% 24% 7% 1	3160
	11th to 20th	Day	58% 5% 9% 19% 9% 1	3140
	21st to end	Day	66% 5% 12% 13% 4	3378
November	1st to 10th	Day	58% 5% 13% 18% 5% 1	1554
	11th to 20th	Day	67% 5% 9% 12% 6% 1	1520
	21st to end	Day	76% 5% 8% 8% 4 1	1520
December	1st to 10th	Day	75% 4 6% 9% 4 1	1520
	11th to 20th	Day	74% 3 6% 8% 7% 1	1906
	21st to end	Day	77% 3 4 12% 4	2772
January	1st to 10th	Night	76% 5% 9% 7% 3	4429
	11th to 20th	Night	75% 6% 7% 7% 4 1	4436
	21st to end	Night	75% 3 6% 8% 6% 1	4532
February	1st to 10th	Night	67% 6% 9% 11% 6% 1	2470
	11th to 20th	Night	63% 4 9% 16% 8% 1	2405
	21st to end	Night	64% 4 7% 16% 8% 1	2003
March	1st to 10th	Night	58% 5% 10% 14% 11% 1	3480
	11th to 20th	Night	61% 5% 12% 15% 7% 1	3480
	21st to end	Night	51% 5% 8% 21% 13% 2	3790
April	1st to 10th	Night	57% 4 7% 18% 12% 2	1900
	11th to 20th	Night	51% 5% 6% 23% 14% 1	1834
	21st to end	Night	55% 5% 7% 16% 15% 2	1710
May	1st to 10th	Night	47% 6% 12% 24% 10% 1	2653
	11th to 20th	Night	45% 7% 11% 25% 11% 1	2496
	21st to end	Night	43% 5% 12% 24% 15% 1	2739
June	1st to 10th	Night	49% 5% 11% 20% 13% 1	1520
	11th to 20th	Night	39% 5% 13% 26% 15% 1	1397
	21st to end	Night	47% 6% 14% 21% 11% 1	1330
July	1st to 10th	Night	42% 7% 15% 22% 14% 1	2204
	11th to 20th	Night	41% 6% 13% 31% 9% 1	2472
	21st to end	Night	34% 6% 12% 32% 14% 1	2677
August	1st to 10th	Night	36% 7% 17% 26% 13% 1	2814
	11th to 20th	Night	43% 7% 18% 25% 7%	2812
	21st to end	Night	34% 6% 15% 32% 11% 2	3283
September	1st to 10th	Night	36% 8% 15% 28% 12% 1	1900
	11th to 20th	Night	39% 5% 13% 30% 13%	1938
	21st to end	Night	46% 6% 12% 26% 10%	2171
October	1st to 10th	Night	43% 5% 10% 28% 14%	3800
	11th to 20th	Night	53% 5% 12% 18% 11%	3779
	21st to end	Night	59% 5% 17% 13% 5%	4168
November	1st to 10th	Night	58% 5% 12% 18% 6%	2593
	11th to 20th	Night	63% 6% 12% 12% 6% 1	2660
	21st to end	Night	72% 5% 10% 9% 4	2660
December	1st to 10th	Night	78% 5% 6% 8% 3	2660
	11th to 20th	Night	72% 4 6% 12% 7%	3288
	21st to end	Night	80% 3 5% 7% 4	4884

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	26% 24% 32% 12% 4 1	180
	11th to 20th	Day	29% 19% 34% 13% 3 1	180
	21st to end	Day	26% 19% 36% 14% 5%	297
February	1st to 10th	Day	28% 29% 33% 6% 3	270
	11th to 20th	Day	26% 33% 34% 7%	270
	21st to end	Day	37% 23% 31% 8% 1	263
March	1st to 10th	Day	25% 23% 37% 13% 2	460
	11th to 20th	Day	24% 24% 34% 13% 4 1	460
	21st to end	Day	27% 24% 30% 14% 4	506
April	1st to 10th	Day	27% 23% 33% 12% 4 1	460
	11th to 20th	Day	34% 21% 22% 13% 7% 3	452
	21st to end	Day	29% 20% 31% 13% 6% 1	460
May	1st to 10th	Day	27% 16% 29% 20% 6% 2	463
	11th to 20th	Day	22% 18% 29% 20% 8% 2	487
	21st to end	Day	20% 18% 30% 21% 7% 2	529
June	1st to 10th	Day	25% 13% 35% 21% 5% 1	490
	11th to 20th	Day	17% 14% 37% 21% 10% 2	608
	21st to end	Day	23% 14% 34% 21% 8% 1	680
July	1st to 10th	Day	14% 12% 35% 29% 9% 1	649
	11th to 20th	Day	17% 13% 33% 24% 10% 3	484
	21st to end	Day	13% 13% 33% 28% 10% 3	532
August	1st to 10th	Day	17% 10% 31% 27% 9% 6%	486
	11th to 20th	Day	16% 9% 27% 29% 13% 6%	479
	21st to end	Day	17% 13% 33% 22% 11% 4	539
September	1st to 10th	Day	19% 12% 33% 20% 12% 5%	490
	11th to 20th	Day	19% 9% 25% 22% 16% 9%	490
	21st to end	Day	23% 16% 26% 21% 11% 3	490
October	1st to 10th	Day	26% 19% 26% 16% 11% 2	490
	11th to 20th	Day	30% 22% 30% 12% 4 1	490
	21st to end	Day	38% 18% 27% 14% 2	524
November	1st to 10th	Day	30% 23% 32% 12% 3	230
	11th to 20th	Day	34% 19% 31% 11% 4	180
	21st to end	Day	34% 20% 35% 9% 1 1	180
December	1st to 10th	Day	31% 21% 33% 14% 1	180
	11th to 20th	Day	34% 27% 29% 8% 1 1	180
	21st to end	Day	29% 29% 25% 14% 3 1	198
January	1st to 10th	Night	25% 21% 36% 14% 3	760
	11th to 20th	Night	27% 21% 31% 17% 4 1	760
	21st to end	Night	18% 19% 35% 21% 6% 1	836
February	1st to 10th	Night	20% 24% 38% 15% 3	760
	11th to 20th	Night	20% 21% 39% 16% 3	743
	21st to end	Night	23% 23% 32% 19% 3	628
March	1st to 10th	Night	21% 25% 32% 19% 3	760
	11th to 20th	Night	22% 19% 37% 16% 5% 1	760
	21st to end	Night	19% 21% 33% 21% 6%	836
April	1st to 10th	Night	28% 16% 33% 19% 4	760
	11th to 20th	Night	26% 17% 28% 20% 8% 1	710
	21st to end	Night	25% 12% 29% 22% 11%	570
May	1st to 10th	Night	23% 9% 28% 29% 10% 1	461
	11th to 20th	Night	21% 10% 33% 27% 8%	374
	21st to end	Night	16% 10% 36% 28% 10%	411
June	1st to 10th	Night	19% 13% 32% 28% 7% 1	380
	11th to 20th	Night	18% 8% 31% 33% 11% 1	380
	21st to end	Night	21% 9% 27% 31% 12% 1	380
July	1st to 10th	Night	13% 8% 32% 32% 15% 1	370
	11th to 20th	Night	15% 6% 28% 36% 14% 1	368
	21st to end	Night	12% 6% 34% 35% 13% 1	430
August	1st to 10th	Night	14% 5% 25% 36% 18% 2	567
	11th to 20th	Night	12% 7% 23% 34% 22% 3	564
	21st to end	Night	16% 8% 30% 27% 17% 2	721
September	1st to 10th	Night	14% 9% 31% 28% 16% 2	760
	11th to 20th	Night	20% 7% 25% 25% 18% 4	760
	21st to end	Night	23% 11% 23% 27% 14% 2	760
October	1st to 10th	Night	26% 15% 25% 21% 10% 2	760
	11th to 20th	Night	29% 17% 30% 16% 7% 1	760
	21st to end	Night	33% 18% 30% 16% 4	836
November	1st to 10th	Night	29% 17% 30% 19% 5% 1	755
	11th to 20th	Night	26% 24% 28% 16% 6%	760
	21st to end	Night	31% 20% 28% 17% 4	760
December	1st to 10th	Night	33% 20% 34% 10% 3	760
	11th to 20th	Night	27% 23% 33% 14% 2 1	760
	21st to end	Night	33% 19% 30% 14% 3	836

Page generated at 2024-11-01 22:47:35. Version ac07

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