Lake of Three Fires State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake of Three Fires State Park clear sky chart from 2005-11-06 to 2026-09-14.

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	11% 7% 3 7% 5% 4 4 4 5% 7% 42%	149082
	Night	10% 7% 3 7% 4 4 4 3 5% 7% 46%	142389
Transparency	Day	39% 5% 13% 25% 15% 2	152690
	Night	38% 5% 12% 25% 17% 3	146861
Seeing	Day	14% 11% 31% 28% 13% 3	18393
	Night	14% 10% 34% 31% 11% 1	28128

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	10% 11% 4 13% 7% 5% 5% 3 5% 6% 31%	5148
	11th to 20th	Day	5% 8% 3 10% 6% 5% 8% 4 5% 6% 39%	5310
	21st to end	Day	8% 12% 5% 13% 6% 5% 4 3 4 6% 33%	5812
February	1st to 10th	Day	11% 11% 4 9% 7% 6% 6% 4 4 8% 31%	1890
	11th to 20th	Day	11% 9% 4 8% 6% 5% 5% 3 5% 7% 38%	1844
	21st to end	Day	11% 9% 3 7% 6% 5% 3 4 4 8% 41%	1724
March	1st to 10th	Day	16% 9% 3 7% 3 3 3 2 3 4 47%	5046
	11th to 20th	Day	10% 7% 3 6% 4 4 4 3 5% 8% 47%	5090
	21st to end	Day	15% 13% 5% 10% 5% 4 5% 4 5% 7% 28%	5583
April	1st to 10th	Day	17% 10% 3 7% 4 3 3 3 5% 6% 40%	2442
	11th to 20th	Day	16% 9% 2 6% 4 4 4 4 5% 6% 38%	2494
	21st to end	Day	19% 8% 3 7% 4 4 4 3 6% 7% 36%	2723
May	1st to 10th	Day	11% 8% 3 7% 4 4 4 4 6% 8% 42%	7617
	11th to 20th	Day	13% 6% 2 6% 3 3 4 3 5% 6% 47%	7627
	21st to end	Day	17% 8% 3 7% 4 4 4 3 5% 7% 37%	9043
June	1st to 10th	Day	9% 5% 2 6% 4 5% 5% 4 6% 9% 46%	2940
	11th to 20th	Day	8% 5% 2 6% 5% 4 4 4 7% 9% 46%	2940
	21st to end	Day	8% 5% 2 6% 4 6% 5% 4 6% 9% 44%	2940
July	1st to 10th	Day	9% 5% 2 6% 4 4 5% 4 8% 10% 42%	8206
	11th to 20th	Day	6% 4 2 5% 4 4 4 3 6% 8% 56%	7680
	21st to end	Day	9% 5% 2 5% 4 4 5% 4 7% 10% 43%	8337
August	1st to 10th	Day	6% 4 2 6% 4 4 5% 4 8% 9% 47%	6014
	11th to 20th	Day	10% 7% 3 8% 5% 5% 5% 4 6% 9% 38%	5948
	21st to end	Day	6% 5% 2 6% 4 5% 5% 4 7% 9% 48%	6288
September	1st to 10th	Day	11% 4 2 4 3 3 3 3 5% 7% 53%	2520
	11th to 20th	Day	8% 5% 3 5% 4 4 5% 5% 5% 8% 49%	2272
	21st to end	Day	10% 5% 1 4 3 3 3 3 5% 6% 55%	2180
October	1st to 10th	Day	13% 7% 2 5% 3 3 3 3 4 5% 52%	2000
	11th to 20th	Day	12% 7% 2 7% 2 3 2 3 4 5% 53%	2000
	21st to end	Day	13% 9% 3 6% 4 4 3 4 5% 6% 44%	2200
November	1st to 10th	Day	9% 7% 2 5% 4 3 4 3 4 7% 52%	1990
	11th to 20th	Day	11% 8% 2 7% 4 4 4 3 4 7% 45%	1706
	21st to end	Day	15% 10% 4 5% 4 3 4 3 6% 7% 39%	1680
December	1st to 10th	Day	5% 5% 2 7% 6% 4 4 3 5% 7% 51%	2690
	11th to 20th	Day	11% 10% 4 9% 6% 4 4 3 5% 6% 40%	3088
	21st to end	Day	19% 11% 6% 14% 5% 4 4 4 5% 6% 22%	4070
January	1st to 10th	Night	10% 10% 4 17% 7% 5% 4 3 5% 6% 30%	7770
	11th to 20th	Night	6% 7% 3 9% 5% 5% 7% 4 7% 6% 42%	7680
	21st to end	Night	9% 13% 5% 11% 4 5% 4 3 4 5% 38%	8402
February	1st to 10th	Night	11% 11% 4 8% 5% 5% 4 4 5% 6% 37%	2730
	11th to 20th	Night	10% 10% 3 7% 5% 4 4 3 5% 8% 41%	2663
	21st to end	Night	10% 8% 3 7% 4 4 4 3 5% 4 47%	2100
March	1st to 10th	Night	15% 7% 3 6% 3 3 3 3 4 5% 49%	5029
	11th to 20th	Night	10% 6% 2 5% 3 3 3 3 4 6% 54%	5090
	21st to end	Night	14% 11% 4 9% 5% 4 4 4 6% 6% 33%	5588
April	1st to 10th	Night	12% 8% 3 6% 5% 3 4 3 5% 7% 45%	2177
	11th to 20th	Night	12% 8% 3 6% 4 4 4 4 4 6% 45%	2075
	21st to end	Night	16% 8% 3 7% 4 3 3 3 4 6% 44%	1894
May	1st to 10th	Night	11% 6% 2 6% 4 4 4 3 5% 7% 49%	5266
	11th to 20th	Night	14% 5% 2 5% 3 3 3 3 4 7% 51%	5265
	21st to end	Night	17% 7% 3 7% 4 4 3 3 5% 6% 40%	5143
June	1st to 10th	Night	6% 4 3 4 4 3 3 4 6% 10% 53%	1680
	11th to 20th	Night	6% 4 1 5% 3 4 4 5% 8% 11% 51%	1680
	21st to end	Night	5% 4 2 4 3 4 5% 4 5% 9% 54%	1680
July	1st to 10th	Night	6% 5% 2 5% 4 4 5% 4 6% 9% 49%	4764
	11th to 20th	Night	4 3 1 5% 4 3 4 3 5% 8% 59%	5307
	21st to end	Night	8% 5% 2 5% 4 4 5% 4 8% 10% 44%	5770
August	1st to 10th	Night	6% 4 2 5% 3 4 4 3 6% 8% 56%	4156
	11th to 20th	Night	11% 6% 2 6% 4 4 4 3 5% 8% 47%	4118
	21st to end	Night	5% 4 2 5% 3 3 4 3 4 9% 57%	4846
September	1st to 10th	Night	9% 4 2 5% 3 3 3 3 5% 6% 58%	2100
	11th to 20th	Night	10% 4 2 4 3 3 3 3 5% 8% 55%	2191
	21st to end	Night	9% 4 2 4 2 3 3 3 4 7% 59%	2200
October	1st to 10th	Night	13% 7% 2 4 3 3 3 3 5% 6% 53%	2400
	11th to 20th	Night	13% 6% 2 5% 3 3 3 2 4 6% 54%	2400
	21st to end	Night	14% 6% 2 5% 4 3 3 2 4 5% 50%	2640
November	1st to 10th	Night	9% 5% 2 4 3 3 4 3 6% 6% 55%	2523
	11th to 20th	Night	9% 8% 2 6% 4 4 3 4 5% 6% 49%	2913
	21st to end	Night	14% 9% 3 5% 4 2 3 3 5% 6% 46%	2940
December	1st to 10th	Night	6% 7% 2 7% 4 4 4 3 5% 6% 50%	4720
	11th to 20th	Night	10% 8% 4 9% 5% 4 4 3 5% 7% 42%	5339
	21st to end	Night	17% 16% 6% 13% 4 4 3 3 3 5% 27%	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	52% 5% 11% 18% 12% 1	5149
	11th to 20th	Day	46% 5% 9% 21% 15% 5%	5310
	21st to end	Day	53% 4 12% 21% 10% 1	5812
February	1st to 10th	Day	52% 5% 12% 20% 10% 2	1890
	11th to 20th	Day	45% 6% 12% 22% 13% 2	1853
	21st to end	Day	41% 5% 12% 24% 15% 2	1724
March	1st to 10th	Day	43% 3 8% 24% 18% 4	5046
	11th to 20th	Day	36% 5% 9% 24% 23% 3	5090
	21st to end	Day	55% 7% 17% 15% 4 2	5585
April	1st to 10th	Day	45% 5% 11% 26% 12% 1	2442
	11th to 20th	Day	45% 5% 12% 22% 14% 2	2494
	21st to end	Day	48% 6% 11% 23% 12% 1	2723
May	1st to 10th	Day	39% 6% 10% 26% 18% 1	7655
	11th to 20th	Day	37% 5% 10% 28% 17% 3	7631
	21st to end	Day	46% 6% 10% 23% 15% 1	9057
June	1st to 10th	Day	34% 7% 16% 27% 13% 3	2940
	11th to 20th	Day	32% 7% 15% 26% 18% 1	2940
	21st to end	Day	35% 7% 16% 26% 14% 3	2940
July	1st to 10th	Day	35% 6% 17% 31% 11% 1	8138
	11th to 20th	Day	27% 5% 15% 29% 20% 3	7611
	21st to end	Day	34% 7% 19% 30% 9% 1	8155
August	1st to 10th	Day	31% 6% 14% 30% 17% 1	6000
	11th to 20th	Day	43% 6% 16% 25% 10%	5987
	21st to end	Day	32% 6% 16% 32% 12% 3	6287
September	1st to 10th	Day	30% 5% 12% 28% 20% 4	2520
	11th to 20th	Day	31% 7% 13% 29% 19% 1	2272
	21st to end	Day	29% 5% 10% 31% 24% 1	2180
October	1st to 10th	Day	22% 3 6% 21% 46% 2	3260
	11th to 20th	Day	22% 3 7% 30% 30% 7%	3240
	21st to end	Day	36% 4 10% 26% 21% 3	3538
November	1st to 10th	Day	33% 4 15% 26% 19% 3	1990
	11th to 20th	Day	39% 4 12% 26% 17% 2	1706
	21st to end	Day	44% 5% 12% 26% 12% 1	1680
December	1st to 10th	Day	33% 4 18% 30% 14% 1	2690
	11th to 20th	Day	45% 4 14% 26% 10% 1	3085
	21st to end	Day	63% 4 12% 15% 5%	4070
January	1st to 10th	Night	55% 5% 12% 17% 9% 1	7771
	11th to 20th	Night	39% 4 11% 24% 19% 3	7680
	21st to end	Night	50% 4 12% 17% 14% 3	8402
February	1st to 10th	Night	47% 5% 12% 21% 13% 3	2730
	11th to 20th	Night	42% 5% 11% 24% 15% 3	2664
	21st to end	Night	38% 5% 11% 22% 20% 5%	2100
March	1st to 10th	Night	39% 4 7% 25% 23% 2	5029
	11th to 20th	Night	32% 4 7% 30% 22% 6%	5090
	21st to end	Night	49% 7% 17% 20% 6% 1	5588
April	1st to 10th	Night	37% 5% 12% 26% 16% 3	2177
	11th to 20th	Night	40% 5% 11% 25% 15% 4	2075
	21st to end	Night	43% 6% 12% 24% 15% 2	1894
May	1st to 10th	Night	35% 5% 9% 26% 22% 3	5293
	11th to 20th	Night	35% 5% 11% 24% 22% 4	5266
	21st to end	Night	44% 5% 10% 24% 15% 1	5153
June	1st to 10th	Night	26% 7% 19% 31% 14% 3	1680
	11th to 20th	Night	25% 7% 16% 27% 21% 4	1680
	21st to end	Night	26% 7% 17% 28% 18% 3	1680
July	1st to 10th	Night	31% 5% 15% 29% 17% 3	4726
	11th to 20th	Night	24% 5% 17% 29% 20% 5%	5256
	21st to end	Night	32% 7% 20% 29% 11% 1	5641
August	1st to 10th	Night	26% 5% 14% 33% 21% 1	4146
	11th to 20th	Night	36% 5% 18% 26% 14% 1	4145
	21st to end	Night	25% 4 16% 34% 16% 5%	4846
September	1st to 10th	Night	28% 4 11% 26% 24% 6%	2100
	11th to 20th	Night	28% 5% 12% 32% 21% 2	2191
	21st to end	Night	27% 4 9% 31% 26% 3	2200
October	1st to 10th	Night	22% 3 6% 19% 48% 2	3920
	11th to 20th	Night	24% 3 7% 28% 30% 8%	3899
	21st to end	Night	37% 3 8% 26% 24% 2	4252
November	1st to 10th	Night	28% 5% 16% 26% 21% 4	2523
	11th to 20th	Night	34% 5% 11% 29% 17% 3	2913
	21st to end	Night	40% 4 11% 28% 16% 2	2940
December	1st to 10th	Night	34% 4 12% 37% 13% 1	4720
	11th to 20th	Night	42% 5% 13% 27% 13% 1	5341
	21st to end	Night	61% 4 10% 18% 6% 1	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	18% 15% 37% 24% 5% 1	330
	11th to 20th	Day	16% 19% 42% 18% 5%	330
	21st to end	Day	15% 12% 48% 21% 4	363
February	1st to 10th	Day	14% 20% 43% 19% 3 1	330
	11th to 20th	Day	18% 18% 40% 19% 5%	330
	21st to end	Day	14% 22% 44% 18% 3	273
March	1st to 10th	Day	21% 17% 41% 18% 2	330
	11th to 20th	Day	25% 17% 32% 22% 4	330
	21st to end	Day	31% 20% 32% 14% 3	363
April	1st to 10th	Day	24% 17% 37% 17% 5%	462
	11th to 20th	Day	21% 17% 36% 19% 6%	532
	21st to end	Day	22% 17% 34% 19% 7% 1	743
May	1st to 10th	Day	17% 13% 34% 25% 8% 2	753
	11th to 20th	Day	19% 11% 32% 26% 11% 2	775
	21st to end	Day	19% 11% 27% 27% 13% 3	844
June	1st to 10th	Day	9% 6% 22% 34% 22% 7%	780
	11th to 20th	Day	8% 6% 31% 35% 18% 3	780
	21st to end	Day	9% 8% 37% 30% 14% 2	780
July	1st to 10th	Day	7% 4 17% 35% 27% 9%	771
	11th to 20th	Day	6% 3 22% 38% 24% 8%	768
	21st to end	Day	8% 2 20% 41% 24% 5%	849
August	1st to 10th	Day	7% 4 23% 40% 21% 5%	776
	11th to 20th	Day	10% 4 19% 40% 23% 5%	765
	21st to end	Day	10% 3 20% 37% 24% 6%	722
September	1st to 10th	Day	14% 5% 23% 31% 22% 5%	570
	11th to 20th	Day	8% 3 25% 40% 18% 6%	378
	21st to end	Day	13% 8% 29% 30% 15% 4	330
October	1st to 10th	Day	21% 6% 27% 30% 12% 5%	330
	11th to 20th	Day	13% 21% 39% 20% 6% 1	330
	21st to end	Day	18% 18% 33% 21% 7% 2	363
November	1st to 10th	Day	14% 13% 46% 19% 6% 2	330
	11th to 20th	Day	18% 17% 38% 19% 8% 1	330
	21st to end	Day	21% 15% 36% 20% 7%	330
December	1st to 10th	Day	8% 17% 42% 27% 6% 1	330
	11th to 20th	Day	18% 18% 34% 25% 5% 1	330
	21st to end	Day	23% 18% 38% 18% 2	363
January	1st to 10th	Night	12% 13% 39% 29% 7%	1050
	11th to 20th	Night	14% 15% 41% 24% 5% 1	1050
	21st to end	Night	16% 12% 42% 25% 5%	1155
February	1st to 10th	Night	16% 13% 42% 26% 4	1050
	11th to 20th	Night	15% 14% 41% 26% 4	1029
	21st to end	Night	15% 15% 44% 20% 5% 1	716
March	1st to 10th	Night	16% 15% 39% 24% 5%	630
	11th to 20th	Night	19% 10% 41% 24% 6%	630
	21st to end	Night	23% 13% 42% 18% 4	693
April	1st to 10th	Night	14% 16% 40% 26% 4	630
	11th to 20th	Night	17% 15% 40% 25% 4	623
	21st to end	Night	21% 12% 36% 24% 6%	630
May	1st to 10th	Night	17% 10% 32% 33% 7%	630
	11th to 20th	Night	16% 9% 33% 29% 11% 1	621
	21st to end	Night	15% 7% 29% 35% 14%	683
June	1st to 10th	Night	6% 4 26% 44% 19% 1	630
	11th to 20th	Night	7% 4 28% 45% 16%	630
	21st to end	Night	8% 4 34% 40% 13%	630
July	1st to 10th	Night	5% 3 17% 42% 31% 2	615
	11th to 20th	Night	4 2 19% 46% 28% 1	612
	21st to end	Night	5% 2 17% 48% 27% 1	690
August	1st to 10th	Night	6% 3 18% 50% 21% 2	627
	11th to 20th	Night	9% 4 13% 46% 26% 3	624
	21st to end	Night	6% 3 17% 45% 26% 2	693
September	1st to 10th	Night	10% 3 22% 39% 23% 2	630
	11th to 20th	Night	11% 2 23% 39% 22% 1	609
	21st to end	Night	10% 5% 28% 41% 16% 1	600
October	1st to 10th	Night	16% 6% 31% 32% 14% 2	800
	11th to 20th	Night	15% 11% 38% 29% 7%	800
	21st to end	Night	17% 13% 35% 27% 7%	880
November	1st to 10th	Night	11% 12% 36% 33% 8%	883
	11th to 20th	Night	14% 15% 40% 26% 5%	1050
	21st to end	Night	19% 13% 36% 26% 7%	1050
December	1st to 10th	Night	15% 13% 39% 27% 6%	1050
	11th to 20th	Night	17% 12% 38% 28% 6%	1050
	21st to end	Night	21% 13% 38% 25% 3	1155

Page generated at 2026-09-11 03:11:58. Version ac07

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