Lake Harris Campground
Clear Sky Chart
History

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

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 10% 6% 5% 5% 4 5% 6% 26%	132144
	Night	16% 13% 5% 12% 7% 5% 4 3 5% 5% 24%	130990
Transparency	Day	55% 7% 11% 17% 9% 1	135610
	Night	58% 7% 11% 15% 8% 1	135611
Seeing	Day	27% 18% 27% 17% 8% 3	16620
	Night	25% 17% 25% 23% 9% 1	25726

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% 16% 7% 20% 13% 6% 4 3 3 4 14%	4661
	11th to 20th	Day	9% 16% 9% 21% 12% 8% 4 2 3 2 14%	4650
	21st to end	Day	9% 14% 8% 15% 9% 8% 7% 4 5% 5% 16%	5226
February	1st to 10th	Day	13% 17% 6% 14% 9% 6% 5% 5% 5% 5% 18%	1890
	11th to 20th	Day	12% 13% 8% 16% 9% 6% 4 4 5% 4 20%	1967
	21st to end	Day	15% 17% 6% 13% 6% 5% 5% 2 4 6% 20%	1730
March	1st to 10th	Day	18% 16% 7% 17% 5% 4 3 2 3 3 21%	4576
	11th to 20th	Day	13% 16% 7% 12% 6% 4 5% 3 4 5% 27%	4855
	21st to end	Day	21% 13% 5% 9% 6% 4 4 3 3 4 29%	6054
April	1st to 10th	Day	20% 14% 5% 9% 5% 4 4 3 4 5% 27%	2520
	11th to 20th	Day	18% 14% 4 8% 4 5% 4 3 4 5% 31%	2494
	21st to end	Day	21% 13% 4 9% 4 4 5% 3 4 5% 28%	2630
May	1st to 10th	Day	31% 13% 4 7% 4 4 4 3 4 5% 20%	6316
	11th to 20th	Day	18% 13% 3 9% 5% 5% 5% 4 5% 6% 26%	6458
	21st to end	Day	20% 10% 4 8% 6% 5% 5% 4 6% 6% 26%	7103
June	1st to 10th	Day	21% 8% 3 8% 7% 5% 5% 4 6% 7% 26%	2800
	11th to 20th	Day	18% 8% 3 7% 6% 5% 5% 6% 7% 7% 28%	2800
	21st to end	Day	21% 9% 3 8% 5% 5% 5% 4 6% 7% 27%	2800
July	1st to 10th	Day	12% 6% 3 7% 5% 6% 6% 5% 8% 10% 33%	6360
	11th to 20th	Day	12% 8% 3 7% 5% 6% 5% 5% 7% 9% 33%	6360
	21st to end	Day	14% 6% 2 6% 5% 5% 5% 5% 6% 9% 37%	6926
August	1st to 10th	Day	17% 8% 3 7% 5% 5% 6% 5% 7% 8% 30%	4563
	11th to 20th	Day	17% 8% 3 9% 5% 5% 6% 5% 7% 8% 28%	3954
	21st to end	Day	16% 6% 3 6% 5% 5% 5% 5% 7% 9% 33%	4312
September	1st to 10th	Day	16% 6% 2 6% 5% 5% 4 4 5% 7% 39%	2400
	11th to 20th	Day	15% 6% 2 5% 4 3 4 4 5% 7% 44%	2327
	21st to end	Day	20% 7% 2 6% 3 4 4 4 6% 7% 36%	2200
October	1st to 10th	Day	23% 12% 3 6% 4 5% 3 3 4 5% 31%	2052
	11th to 20th	Day	19% 14% 3 7% 3 5% 4 4 6% 7% 29%	2000
	21st to end	Day	24% 15% 5% 9% 4 5% 4 2 5% 5% 23%	1983
November	1st to 10th	Day	15% 15% 4 9% 6% 5% 5% 3 5% 5% 27%	1851
	11th to 20th	Day	16% 15% 7% 9% 5% 4 4 4 4 5% 26%	1852
	21st to end	Day	18% 18% 7% 10% 6% 4 5% 3 4 5% 20%	1680
December	1st to 10th	Day	17% 25% 8% 18% 8% 4 2 2 2 3 11%	2680
	11th to 20th	Day	17% 21% 6% 15% 6% 4 3 3 3 5% 17%	3066
	21st to end	Day	17% 17% 7% 14% 5% 3 3 3 4 5% 22%	4048
January	1st to 10th	Night	12% 14% 9% 21% 10% 6% 3 3 4 4 14%	8234
	11th to 20th	Night	9% 16% 10% 22% 14% 7% 4 3 3 3 8%	8235
	21st to end	Night	9% 13% 7% 17% 9% 11% 9% 5% 5% 4 12%	8941
February	1st to 10th	Night	12% 15% 5% 15% 10% 7% 6% 4 5% 4 18%	2730
	11th to 20th	Night	11% 12% 5% 16% 10% 7% 5% 4 5% 6% 18%	2538
	21st to end	Night	12% 15% 6% 14% 8% 6% 5% 4 5% 5% 20%	2076
March	1st to 10th	Night	19% 15% 4 12% 8% 6% 5% 3 4 5% 20%	5484
	11th to 20th	Night	14% 14% 6% 11% 5% 4 3 3 4 6% 30%	5306
	21st to end	Night	20% 14% 6% 12% 6% 4 3 2 3 4 25%	5119
April	1st to 10th	Night	21% 11% 5% 9% 6% 4 4 4 4 5% 27%	2100
	11th to 20th	Night	19% 13% 4 8% 5% 4 3 3 5% 5% 29%	2075
	21st to end	Night	18% 10% 5% 9% 5% 4 4 3 5% 6% 32%	1990
May	1st to 10th	Night	30% 13% 3 8% 4 4 4 3 4 5% 21%	3875
	11th to 20th	Night	19% 15% 4 8% 4 4 4 3 4 7% 29%	3655
	21st to end	Night	16% 12% 4 8% 5% 5% 5% 4 5% 6% 29%	4014
June	1st to 10th	Night	20% 8% 2 7% 5% 4 4 4 5% 7% 34%	1600
	11th to 20th	Night	18% 7% 2 6% 5% 4 4 4 5% 8% 36%	1600
	21st to end	Night	19% 8% 2 6% 5% 5% 5% 5% 7% 7% 33%	1600
July	1st to 10th	Night	12% 7% 2 7% 5% 6% 6% 4 6% 8% 36%	3600
	11th to 20th	Night	15% 9% 3 7% 4 4 4 3 5% 7% 37%	3600
	21st to end	Night	9% 6% 3 6% 4 4 4 4 6% 10% 44%	3926
August	1st to 10th	Night	18% 9% 4 8% 4 4 4 3 4 6% 37%	2586
	11th to 20th	Night	18% 9% 3 7% 4 4 4 3 6% 7% 36%	3057
	21st to end	Night	12% 6% 2 6% 4 5% 5% 5% 7% 9% 38%	3586
September	1st to 10th	Night	14% 8% 3 6% 4 3 4 3 4 7% 43%	2000
	11th to 20th	Night	13% 6% 2 6% 4 4 3 4 5% 7% 46%	2071
	21st to end	Night	18% 9% 2 5% 4 4 4 3 5% 7% 39%	2200
October	1st to 10th	Night	21% 10% 4 7% 5% 4 4 3 5% 6% 31%	2345
	11th to 20th	Night	17% 13% 3 8% 4 5% 4 4 5% 7% 30%	2400
	21st to end	Night	21% 15% 5% 9% 6% 5% 5% 4 4 5% 22%	2855
November	1st to 10th	Night	14% 14% 5% 10% 5% 4 5% 4 6% 6% 26%	2667
	11th to 20th	Night	17% 14% 5% 10% 6% 4 5% 4 4 5% 26%	2767
	21st to end	Night	17% 16% 6% 13% 6% 5% 4 4 6% 5% 18%	2940
December	1st to 10th	Night	16% 20% 9% 21% 7% 4 4 3 3 3 9%	4720
	11th to 20th	Night	21% 18% 6% 13% 6% 4 4 3 3 3 18%	5348
	21st to end	Night	19% 18% 5% 14% 5% 4 3 3 4 5% 19%	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	72% 5% 8% 11% 3	4662
	11th to 20th	Day	76% 4 5% 6% 8% 2	4680
	21st to end	Day	66% 7% 10% 10% 6% 1	5226
February	1st to 10th	Day	65% 5% 9% 14% 5% 2	1890
	11th to 20th	Day	65% 5% 9% 12% 8% 1	1976
	21st to end	Day	64% 5% 10% 11% 9% 1	1730
March	1st to 10th	Day	66% 6% 7% 8% 9% 3	4579
	11th to 20th	Day	59% 5% 13% 13% 8% 3	4855
	21st to end	Day	58% 5% 6% 12% 16% 3	6054
April	1st to 10th	Day	59% 4 9% 15% 11% 2	2520
	11th to 20th	Day	55% 5% 8% 18% 13% 1	2494
	21st to end	Day	58% 5% 9% 15% 11% 3	2630
May	1st to 10th	Day	65% 6% 7% 15% 7% 1	6327
	11th to 20th	Day	55% 8% 11% 16% 8% 1	6462
	21st to end	Day	53% 9% 11% 20% 7% 1	7103
June	1st to 10th	Day	54% 8% 12% 15% 10% 1	2800
	11th to 20th	Day	50% 8% 12% 19% 10% 1	2800
	21st to end	Day	54% 8% 12% 17% 9% 1	2800
July	1st to 10th	Day	40% 9% 17% 22% 11%	6290
	11th to 20th	Day	41% 10% 15% 24% 9%	6285
	21st to end	Day	40% 8% 13% 32% 7%	6728
August	1st to 10th	Day	46% 9% 15% 19% 10%	4549
	11th to 20th	Day	46% 10% 17% 21% 5%	3993
	21st to end	Day	41% 9% 17% 24% 9% 1	4312
September	1st to 10th	Day	42% 6% 11% 30% 10% 1	2400
	11th to 20th	Day	38% 5% 12% 28% 17% 1	2327
	21st to end	Day	46% 7% 13% 21% 12% 1	2200
October	1st to 10th	Day	49% 6% 11% 23% 11% 1	3338
	11th to 20th	Day	47% 6% 14% 18% 15% 1	3240
	21st to end	Day	47% 6% 14% 25% 6% 1	3183
November	1st to 10th	Day	56% 7% 12% 16% 9%	1851
	11th to 20th	Day	58% 5% 9% 15% 9% 3	1852
	21st to end	Day	66% 5% 12% 12% 4	1680
December	1st to 10th	Day	79% 3 7% 8% 2	2680
	11th to 20th	Day	68% 5% 9% 13% 4	3066
	21st to end	Day	63% 5% 7% 10% 13% 1	4048
January	1st to 10th	Night	71% 5% 10% 8% 4	8234
	11th to 20th	Night	79% 6% 6% 5% 4 1	8280
	21st to end	Night	70% 7% 9% 9% 6% 1	8941
February	1st to 10th	Night	66% 5% 10% 12% 6% 1	2730
	11th to 20th	Night	62% 5% 11% 13% 7% 1	2540
	21st to end	Night	61% 6% 12% 12% 8% 1	2076
March	1st to 10th	Night	63% 7% 9% 10% 9% 2	5494
	11th to 20th	Night	54% 5% 17% 14% 8% 3	5307
	21st to end	Night	61% 5% 6% 14% 12% 2	5119
April	1st to 10th	Night	57% 4 10% 17% 10% 2	2100
	11th to 20th	Night	54% 6% 12% 17% 11%	2075
	21st to end	Night	52% 6% 9% 18% 12% 2	1990
May	1st to 10th	Night	63% 7% 8% 13% 8% 1	3881
	11th to 20th	Night	53% 9% 11% 18% 8% 1	3656
	21st to end	Night	52% 9% 11% 17% 10% 1	4015
June	1st to 10th	Night	48% 6% 14% 21% 9% 1	1600
	11th to 20th	Night	45% 7% 15% 20% 11% 1	1600
	21st to end	Night	47% 8% 14% 22% 9%	1600
July	1st to 10th	Night	42% 9% 18% 21% 11%	3560
	11th to 20th	Night	43% 9% 13% 25% 11%	3552
	21st to end	Night	32% 9% 18% 32% 9%	3809
August	1st to 10th	Night	46% 7% 16% 22% 8%	2576
	11th to 20th	Night	45% 7% 19% 23% 7%	3084
	21st to end	Night	36% 10% 19% 25% 9% 1	3586
September	1st to 10th	Night	38% 8% 15% 27% 11% 1	2000
	11th to 20th	Night	35% 8% 12% 32% 13% 1	2071
	21st to end	Night	43% 6% 13% 24% 12% 2	2200
October	1st to 10th	Night	50% 7% 12% 20% 9%	3839
	11th to 20th	Night	46% 7% 13% 19% 11% 4	3899
	21st to end	Night	52% 6% 14% 21% 6% 1	4605
November	1st to 10th	Night	55% 7% 12% 15% 9% 2	2667
	11th to 20th	Night	57% 6% 11% 15% 9% 3	2767
	21st to end	Night	63% 6% 13% 13% 5% 1	2940
December	1st to 10th	Night	77% 6% 8% 7% 2	4720
	11th to 20th	Night	70% 4 8% 11% 7%	5348
	21st to end	Night	66% 5% 8% 8% 9% 3	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	27% 23% 34% 10% 5%	220
	11th to 20th	Day	30% 25% 34% 9% 2 1	220
	21st to end	Day	25% 30% 30% 11% 3 1	261
February	1st to 10th	Day	35% 29% 28% 6% 1	330
	11th to 20th	Day	36% 25% 29% 9% 1	455
	21st to end	Day	34% 24% 27% 13% 2	446
March	1st to 10th	Day	30% 22% 31% 14% 3	540
	11th to 20th	Day	34% 24% 27% 12% 3 1	540
	21st to end	Day	34% 26% 22% 11% 5% 2	594
April	1st to 10th	Day	39% 19% 24% 12% 5% 1	540
	11th to 20th	Day	37% 20% 22% 14% 6% 2	532
	21st to end	Day	33% 20% 28% 10% 7% 2	540
May	1st to 10th	Day	37% 18% 25% 9% 6% 3	543
	11th to 20th	Day	25% 20% 26% 19% 8% 1	567
	21st to end	Day	23% 18% 32% 16% 9% 3	617
June	1st to 10th	Day	26% 16% 29% 20% 8% 1	530
	11th to 20th	Day	22% 16% 30% 20% 10% 2	530
	21st to end	Day	24% 19% 29% 18% 7% 2	530
July	1st to 10th	Day	18% 10% 31% 26% 12% 3	525
	11th to 20th	Day	13% 12% 35% 26% 12% 3	524
	21st to end	Day	16% 12% 36% 24% 10% 2	576
August	1st to 10th	Day	15% 11% 24% 27% 16% 7%	526
	11th to 20th	Day	18% 10% 27% 21% 15% 8%	519
	21st to end	Day	14% 16% 27% 22% 14% 7%	583
September	1st to 10th	Day	18% 10% 28% 21% 15% 9%	530
	11th to 20th	Day	15% 11% 24% 19% 20% 12%	530
	21st to end	Day	21% 12% 28% 20% 14% 5%	530
October	1st to 10th	Day	29% 13% 20% 19% 14% 5%	530
	11th to 20th	Day	26% 20% 24% 20% 9% 2	530
	21st to end	Day	32% 18% 24% 20% 6%	463
November	1st to 10th	Day	31% 20% 20% 20% 9%	425
	11th to 20th	Day	30% 22% 22% 18% 6% 1	392
	21st to end	Day	35% 24% 28% 11% 1	220
December	1st to 10th	Day	31% 22% 30% 14% 3	220
	11th to 20th	Day	38% 24% 25% 10% 2	220
	21st to end	Day	33% 22% 27% 14% 4 1	242
January	1st to 10th	Night	27% 24% 31% 15% 2	840
	11th to 20th	Night	29% 23% 29% 15% 3	840
	21st to end	Night	19% 25% 30% 21% 5%	924
February	1st to 10th	Night	25% 25% 30% 18% 2	840
	11th to 20th	Night	25% 26% 31% 16% 2	823
	21st to end	Night	25% 22% 32% 18% 3	692
March	1st to 10th	Night	28% 21% 29% 20% 2	840
	11th to 20th	Night	28% 23% 26% 19% 4	840
	21st to end	Night	29% 20% 26% 19% 6% 1	924
April	1st to 10th	Night	30% 18% 28% 20% 4	840
	11th to 20th	Night	29% 19% 26% 19% 6% 1	831
	21st to end	Night	28% 17% 26% 22% 7%	730
May	1st to 10th	Night	30% 15% 22% 23% 10%	517
	11th to 20th	Night	18% 16% 24% 33% 8% 1	414
	21st to end	Night	16% 10% 29% 30% 13% 1	455
June	1st to 10th	Night	24% 10% 23% 31% 12% 1	400
	11th to 20th	Night	21% 7% 22% 36% 14%	400
	21st to end	Night	19% 11% 25% 34% 11% 1	400
July	1st to 10th	Night	14% 6% 24% 37% 18% 1	390
	11th to 20th	Night	15% 7% 21% 38% 17% 2	388
	21st to end	Night	11% 9% 21% 43% 15% 1	438
August	1st to 10th	Night	17% 5% 17% 41% 19% 1	398
	11th to 20th	Night	17% 6% 20% 32% 22% 4	698
	21st to end	Night	16% 9% 20% 33% 21% 1	880
September	1st to 10th	Night	16% 9% 22% 32% 17% 3	800
	11th to 20th	Night	14% 9% 20% 28% 25% 4	800
	21st to end	Night	23% 12% 20% 25% 18% 3	800
October	1st to 10th	Night	26% 14% 21% 22% 16% 2	800
	11th to 20th	Night	25% 17% 20% 28% 10% 1	800
	21st to end	Night	31% 18% 25% 21% 5%	880
November	1st to 10th	Night	25% 18% 25% 24% 7% 1	820
	11th to 20th	Night	30% 19% 23% 19% 8% 2	840
	21st to end	Night	30% 21% 25% 18% 5% 1	840
December	1st to 10th	Night	30% 25% 26% 15% 4	840
	11th to 20th	Night	31% 24% 22% 18% 4 1	840
	21st to end	Night	33% 23% 23% 18% 4	924

Page generated at 2026-05-29 01:53:29. Version ac07

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