Indian Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Indian Lake State Park clear sky chart from 2005-11-06 to 2026-05-17.

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	14% 10% 4 9% 5% 5% 5% 4 6% 7% 33%	131998
	Night	14% 11% 4 9% 5% 4 4 4 5% 6% 33%	130895
Transparency	Day	49% 6% 11% 21% 12% 1	135610
	Night	49% 6% 11% 20% 13% 2	135340
Seeing	Day	18% 11% 27% 23% 14% 7%	17469
	Night	19% 10% 28% 28% 13% 2	27284

By Month

Percentage Cloud Cover SE (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	16% 17% 8% 16% 7% 5% 4 2 4 5% 15%	4691
	11th to 20th	Day	10% 17% 7% 14% 8% 7% 7% 3 3 4 19%	4976
	21st to end	Day	18% 15% 7% 14% 7% 6% 6% 4 4 4 15%	5780
February	1st to 10th	Day	17% 15% 7% 12% 8% 5% 5% 3 4 5% 20%	1922
	11th to 20th	Day	14% 13% 6% 15% 7% 5% 4 3 4 5% 22%	2048
	21st to end	Day	15% 14% 6% 11% 5% 4 3 3 4 7% 28%	1730
March	1st to 10th	Day	18% 15% 7% 11% 4 5% 4 3 3 5% 25%	4668
	11th to 20th	Day	12% 11% 3 7% 5% 4 4 3 5% 7% 39%	5090
	21st to end	Day	18% 13% 5% 10% 6% 5% 4 3 5% 5% 27%	5586
April	1st to 10th	Day	15% 13% 3 9% 6% 4 5% 3 5% 6% 30%	2449
	11th to 20th	Day	16% 9% 3 7% 5% 4 4 4 5% 7% 35%	2606
	21st to end	Day	19% 8% 4 7% 5% 5% 5% 4 6% 7% 33%	2730
May	1st to 10th	Day	22% 9% 4 8% 4 5% 5% 3 5% 6% 29%	5992
	11th to 20th	Day	17% 8% 3 7% 4 4 5% 4 6% 8% 35%	5939
	21st to end	Day	15% 7% 2 6% 5% 5% 5% 4 7% 9% 35%	6433
June	1st to 10th	Day	12% 7% 3 6% 5% 5% 5% 4 5% 9% 38%	2655
	11th to 20th	Day	11% 6% 2 7% 4 4 5% 4 7% 9% 41%	2800
	21st to end	Day	11% 5% 2 6% 5% 5% 6% 5% 8% 9% 39%	2800
July	1st to 10th	Day	9% 6% 3 7% 4 5% 5% 4 7% 10% 41%	6360
	11th to 20th	Day	9% 6% 2 6% 5% 5% 5% 5% 7% 10% 39%	6227
	21st to end	Day	9% 6% 2 7% 5% 5% 6% 5% 7% 10% 37%	6424
August	1st to 10th	Day	8% 5% 2 6% 4 4 4 4 7% 11% 43%	4234
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 5% 9% 11% 40%	4174
	21st to end	Day	7% 5% 2 6% 4 5% 4 5% 7% 10% 46%	4482
September	1st to 10th	Day	11% 6% 2 5% 4 3 4 3 6% 7% 49%	2261
	11th to 20th	Day	9% 5% 3 5% 5% 4 6% 4 6% 8% 46%	2200
	21st to end	Day	16% 8% 2 5% 4 4 4 3 4 6% 44%	2200
October	1st to 10th	Day	12% 7% 2 6% 4 4 4 4 5% 6% 46%	2189
	11th to 20th	Day	15% 7% 2 5% 4 4 5% 4 5% 6% 42%	2000
	21st to end	Day	19% 10% 3 8% 4 5% 5% 3 5% 7% 32%	2055
November	1st to 10th	Day	10% 9% 3 5% 4 4 3 3 5% 6% 47%	1852
	11th to 20th	Day	15% 14% 4 8% 5% 4 4 3 5% 6% 33%	1890
	21st to end	Day	18% 16% 5% 10% 5% 3 3 3 4 5% 28%	1890
December	1st to 10th	Day	15% 16% 5% 10% 6% 5% 4 3 4 4 27%	3020
	11th to 20th	Day	17% 17% 7% 12% 5% 5% 4 3 4 6% 20%	3463
	21st to end	Day	22% 20% 9% 12% 6% 5% 4 2 3 4 12%	4182
January	1st to 10th	Night	14% 18% 8% 17% 7% 5% 4 3 4 4 18%	8232
	11th to 20th	Night	9% 17% 9% 17% 7% 7% 6% 4 4 4 17%	7981
	21st to end	Night	18% 14% 6% 10% 5% 5% 5% 4 5% 6% 23%	8401
February	1st to 10th	Night	19% 14% 5% 10% 6% 5% 4 3 4 5% 25%	2696
	11th to 20th	Night	15% 13% 4 12% 6% 4 4 3 5% 7% 26%	2458
	21st to end	Night	17% 14% 5% 12% 5% 4 3 3 5% 6% 26%	2076
March	1st to 10th	Night	18% 13% 4 7% 4 4 3 3 4 5% 35%	5404
	11th to 20th	Night	11% 7% 3 6% 5% 5% 5% 4 5% 8% 41%	5090
	21st to end	Night	18% 10% 3 8% 4 4 4 4 4 5% 35%	5588
April	1st to 10th	Night	17% 10% 3 7% 5% 3 4 4 6% 7% 34%	2189
	11th to 20th	Night	16% 8% 2 7% 5% 4 5% 4 7% 7% 35%	1962
	21st to end	Night	15% 9% 3 8% 5% 4 4 3 6% 6% 36%	1890
May	1st to 10th	Night	21% 11% 3 9% 5% 4 5% 4 6% 6% 28%	4123
	11th to 20th	Night	16% 7% 2 7% 5% 4 4 3 6% 9% 37%	4086
	21st to end	Night	13% 7% 2 6% 5% 4 4 4 6% 9% 40%	4421
June	1st to 10th	Night	10% 6% 2 5% 5% 5% 4 4 6% 8% 47%	1739
	11th to 20th	Night	8% 7% 2 6% 4 4 4 5% 6% 8% 46%	1600
	21st to end	Night	8% 5% 2 6% 4 3 6% 4 7% 8% 47%	1600
July	1st to 10th	Night	8% 5% 2 7% 4 4 4 4 7% 8% 47%	3618
	11th to 20th	Night	8% 5% 3 6% 5% 4 5% 4 7% 10% 44%	3739
	21st to end	Night	9% 6% 3 6% 5% 5% 5% 4 6% 8% 43%	4427
August	1st to 10th	Night	10% 7% 2 7% 4 5% 5% 4 7% 9% 41%	2915
	11th to 20th	Night	7% 7% 3 7% 4 4 4 4 6% 8% 45%	2875
	21st to end	Night	4 4 2 7% 4 5% 5% 5% 7% 8% 49%	3411
September	1st to 10th	Night	10% 6% 2 5% 3 3 3 3 5% 7% 52%	2117
	11th to 20th	Night	9% 5% 2 5% 3 2 3 3 6% 7% 56%	2200
	21st to end	Night	12% 7% 3 6% 4 5% 5% 4 5% 5% 46%	2200
October	1st to 10th	Night	10% 4 2 5% 4 4 4 4 5% 7% 53%	2210
	11th to 20th	Night	16% 9% 2 7% 4 4 4 3 5% 7% 41%	2400
	21st to end	Night	19% 8% 2 6% 5% 4 4 4 5% 6% 37%	2780
November	1st to 10th	Night	12% 9% 2 7% 3 4 4 3 5% 6% 45%	2666
	11th to 20th	Night	17% 11% 3 8% 4 3 3 3 4 7% 36%	2730
	21st to end	Night	19% 15% 5% 9% 5% 5% 4 4 5% 5% 26%	2730
December	1st to 10th	Night	14% 13% 5% 10% 5% 5% 5% 4 5% 6% 26%	4380
	11th to 20th	Night	18% 17% 8% 13% 4 4 4 3 4 5% 21%	4952
	21st to end	Night	23% 21% 7% 11% 5% 4 4 3 4 5% 14%	7009

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% 4 9% 11% 4	4692
	11th to 20th	Day	72% 3 6% 8% 11% 1	4976
	21st to end	Day	72% 4 7% 10% 6%	5780
February	1st to 10th	Day	67% 4 10% 12% 7%	1922
	11th to 20th	Day	64% 4 9% 14% 8%	2058
	21st to end	Day	57% 4 13% 16% 7% 2	1730
March	1st to 10th	Day	62% 4 7% 19% 7% 1	4668
	11th to 20th	Day	44% 6% 10% 28% 11% 1	5090
	21st to end	Day	58% 6% 11% 18% 7% 1	5586
April	1st to 10th	Day	53% 6% 12% 17% 11%	2449
	11th to 20th	Day	48% 6% 11% 21% 12% 2	2606
	21st to end	Day	49% 7% 12% 20% 10% 1	2730
May	1st to 10th	Day	55% 7% 10% 17% 11% 1	6027
	11th to 20th	Day	46% 7% 13% 22% 10% 1	5943
	21st to end	Day	42% 9% 12% 23% 13% 2	6447
June	1st to 10th	Day	41% 7% 11% 24% 14% 2	2655
	11th to 20th	Day	38% 9% 14% 23% 15% 1	2800
	21st to end	Day	38% 9% 16% 19% 15% 4	2800
July	1st to 10th	Day	38% 6% 9% 28% 17% 2	6291
	11th to 20th	Day	37% 8% 16% 23% 16% 1	6152
	21st to end	Day	39% 8% 14% 20% 17% 2	6240
August	1st to 10th	Day	33% 9% 16% 26% 15% 1	4221
	11th to 20th	Day	34% 8% 12% 32% 14% 1	4213
	21st to end	Day	32% 7% 15% 31% 13% 3	4481
September	1st to 10th	Day	34% 7% 12% 23% 20% 3	2261
	11th to 20th	Day	33% 7% 11% 24% 22% 3	2200
	21st to end	Day	41% 5% 10% 23% 20% 1	2200
October	1st to 10th	Day	26% 5% 11% 32% 24% 1	3566
	11th to 20th	Day	34% 5% 10% 26% 22% 2	3240
	21st to end	Day	42% 4 11% 22% 20% 1	3292
November	1st to 10th	Day	39% 5% 12% 25% 17% 2	1852
	11th to 20th	Day	53% 4 10% 20% 11% 2	1890
	21st to end	Day	60% 4 9% 18% 8% 1	1890
December	1st to 10th	Day	60% 4 13% 18% 4	3020
	11th to 20th	Day	65% 4 11% 13% 5%	3460
	21st to end	Day	76% 4 7% 9% 4	4182
January	1st to 10th	Night	71% 4 7% 14% 4	8233
	11th to 20th	Night	71% 4 7% 9% 7% 1	7981
	21st to end	Night	61% 4 11% 15% 7% 1	8401
February	1st to 10th	Night	62% 5% 10% 16% 7% 1	2696
	11th to 20th	Night	57% 5% 11% 16% 9% 1	2459
	21st to end	Night	61% 4 9% 16% 9% 1	2076
March	1st to 10th	Night	52% 4 8% 25% 10% 1	5404
	11th to 20th	Night	40% 6% 12% 28% 12% 1	5090
	21st to end	Night	49% 6% 9% 23% 13% 1	5588
April	1st to 10th	Night	47% 6% 12% 20% 13% 1	2189
	11th to 20th	Night	45% 7% 12% 17% 16% 3	1962
	21st to end	Night	47% 5% 11% 21% 13% 2	1890
May	1st to 10th	Night	54% 7% 10% 15% 10% 3	4150
	11th to 20th	Night	43% 7% 13% 23% 14% 1	4087
	21st to end	Night	38% 8% 14% 25% 13% 2	4429
June	1st to 10th	Night	35% 7% 13% 22% 22% 2	1739
	11th to 20th	Night	33% 9% 14% 25% 16% 3	1600
	21st to end	Night	32% 9% 16% 24% 17% 3	1600
July	1st to 10th	Night	33% 7% 12% 26% 18% 4	3580
	11th to 20th	Night	35% 7% 15% 26% 17% 1	3694
	21st to end	Night	37% 7% 14% 20% 19% 4	4297
August	1st to 10th	Night	38% 7% 15% 25% 14% 1	2904
	11th to 20th	Night	36% 7% 10% 29% 18%	2902
	21st to end	Night	29% 8% 14% 28% 18% 3	3411
September	1st to 10th	Night	31% 6% 12% 26% 19% 5%	2117
	11th to 20th	Night	28% 5% 10% 27% 27% 3	2200
	21st to end	Night	39% 6% 9% 21% 22% 2	2200
October	1st to 10th	Night	23% 4 8% 30% 33% 2	3613
	11th to 20th	Night	33% 4 10% 26% 24% 2	3899
	21st to end	Night	36% 4 7% 28% 21% 3	4480
November	1st to 10th	Night	40% 5% 10% 24% 19% 2	2666
	11th to 20th	Night	49% 4 10% 21% 13% 3	2730
	21st to end	Night	59% 6% 9% 18% 8% 1	2730
December	1st to 10th	Night	58% 4 11% 20% 6%	4380
	11th to 20th	Night	66% 4 12% 12% 6%	4954
	21st to end	Night	73% 4 8% 11% 3	7009

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	25% 21% 35% 16% 3 1	330
	11th to 20th	Day	23% 25% 37% 10% 4	330
	21st to end	Day	27% 23% 32% 14% 4	363
February	1st to 10th	Day	26% 16% 37% 16% 4 1	330
	11th to 20th	Day	24% 22% 36% 16% 3	330
	21st to end	Day	20% 24% 46% 9% 1	273
March	1st to 10th	Day	25% 19% 37% 16% 2	366
	11th to 20th	Day	26% 16% 34% 18% 5% 1	540
	21st to end	Day	27% 18% 32% 18% 5% 1	594
April	1st to 10th	Day	22% 16% 33% 20% 6% 2	540
	11th to 20th	Day	20% 20% 28% 19% 10% 4	532
	21st to end	Day	23% 11% 33% 21% 10% 2	540
May	1st to 10th	Day	26% 13% 30% 21% 7% 3	543
	11th to 20th	Day	22% 9% 28% 23% 12% 6%	551
	21st to end	Day	12% 7% 27% 25% 19% 9%	573
June	1st to 10th	Day	14% 7% 27% 27% 18% 6%	585
	11th to 20th	Day	13% 6% 24% 29% 21% 7%	730
	21st to end	Day	12% 7% 27% 29% 20% 6%	730
July	1st to 10th	Day	12% 3 18% 30% 20% 17%	721
	11th to 20th	Day	9% 3 22% 29% 22% 15%	663
	21st to end	Day	11% 2 18% 26% 28% 15%	576
August	1st to 10th	Day	10% 3 13% 26% 29% 18%	526
	11th to 20th	Day	13% 4 15% 28% 25% 14%	519
	21st to end	Day	8% 3 16% 27% 31% 16%	583
September	1st to 10th	Day	13% 4 15% 27% 29% 12%	530
	11th to 20th	Day	8% 4 12% 26% 31% 20%	530
	21st to end	Day	20% 9% 19% 24% 18% 10%	530
October	1st to 10th	Day	12% 5% 22% 29% 22% 9%	530
	11th to 20th	Day	17% 13% 30% 25% 12% 3	530
	21st to end	Day	23% 13% 38% 20% 5% 1	438
November	1st to 10th	Day	15% 15% 34% 24% 8% 4	330
	11th to 20th	Day	26% 18% 31% 17% 8%	330
	21st to end	Day	30% 14% 38% 15% 2	330
December	1st to 10th	Day	23% 18% 38% 16% 5%	330
	11th to 20th	Day	24% 18% 41% 15% 2	330
	21st to end	Day	29% 20% 35% 15% 2	363
January	1st to 10th	Night	22% 18% 36% 20% 4	1050
	11th to 20th	Night	25% 19% 37% 15% 4	946
	21st to end	Night	23% 16% 37% 20% 3	924
February	1st to 10th	Night	25% 13% 36% 24% 3	840
	11th to 20th	Night	22% 16% 36% 24% 2	823
	21st to end	Night	23% 16% 39% 18% 3	692
March	1st to 10th	Night	23% 14% 33% 24% 6% 1	840
	11th to 20th	Night	19% 17% 35% 24% 5%	840
	21st to end	Night	25% 13% 31% 25% 6%	924
April	1st to 10th	Night	21% 13% 36% 25% 4 1	719
	11th to 20th	Night	19% 11% 36% 23% 9% 1	623
	21st to end	Night	18% 9% 36% 26% 10% 1	630
May	1st to 10th	Night	23% 9% 30% 30% 9%	630
	11th to 20th	Night	21% 6% 28% 30% 14% 1	609
	21st to end	Night	10% 3 25% 37% 22% 3	650
June	1st to 10th	Night	12% 4 25% 40% 19% 1	600
	11th to 20th	Night	11% 3 20% 42% 23% 1	600
	21st to end	Night	10% 4 20% 40% 25% 2	600
July	1st to 10th	Night	11% 3 12% 41% 28% 6%	585
	11th to 20th	Night	9% 3 15% 40% 30% 4	582
	21st to end	Night	8% 3 12% 40% 34% 3	657
August	1st to 10th	Night	8% 2 12% 40% 33% 5%	597
	11th to 20th	Night	9% 3 10% 41% 32% 5%	594
	21st to end	Night	7% 2 13% 38% 34% 6%	660
September	1st to 10th	Night	13% 3 14% 35% 30% 5%	717
	11th to 20th	Night	10% 4 12% 35% 33% 6%	800
	21st to end	Night	15% 6% 21% 33% 22% 3	800
October	1st to 10th	Night	12% 4 24% 35% 20% 4	800
	11th to 20th	Night	20% 11% 27% 30% 10% 2	800
	21st to end	Night	24% 10% 34% 24% 7%	880
November	1st to 10th	Night	16% 10% 35% 26% 12% 1	820
	11th to 20th	Night	22% 18% 30% 23% 7% 1	840
	21st to end	Night	26% 13% 31% 24% 5% 1	840
December	1st to 10th	Night	24% 15% 35% 21% 4	840
	11th to 20th	Night	25% 13% 36% 20% 5% 1	840
	21st to end	Night	29% 17% 32% 19% 3	1092

Page generated at 2026-05-14 01:59:00. Version ac07

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