Loon Lake Road Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Loon Lake Road Observing Site clear sky chart from 2005-11-06 to 2026-10-29.

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	7% 10% 3 8% 5% 5% 5% 4 6% 7% 38%	153643
	Night	6% 11% 4 9% 5% 5% 5% 4 6% 7% 37%	147129
Transparency	Day	45% 6% 13% 22% 12% 3	153358
	Night	46% 7% 15% 21% 9% 2	146995
Seeing	Day	19% 18% 29% 21% 11% 3	17958
	Night	15% 15% 28% 26% 13% 2	26269

By Month

Percentage Cloud Cover NW (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% 20% 6% 14% 7% 6% 5% 4 6% 6% 16%	4125
	11th to 20th	Day	5% 12% 4 9% 5% 5% 5% 4 7% 8% 36%	4574
	21st to end	Day	5% 14% 4 10% 6% 6% 7% 4 6% 7% 30%	5186
February	1st to 10th	Day	7% 19% 5% 11% 7% 5% 6% 6% 7% 8% 20%	1768
	11th to 20th	Day	5% 18% 6% 13% 7% 6% 6% 4 6% 8% 23%	1845
	21st to end	Day	6% 19% 6% 13% 7% 7% 6% 4 7% 5% 20%	1668
March	1st to 10th	Day	6% 13% 5% 13% 7% 5% 6% 5% 7% 7% 26%	4618
	11th to 20th	Day	4 13% 5% 11% 7% 6% 6% 4 7% 6% 31%	4970
	21st to end	Day	10% 16% 5% 12% 7% 5% 5% 4 7% 7% 22%	5962
April	1st to 10th	Day	8% 15% 5% 11% 7% 7% 7% 5% 6% 7% 22%	2520
	11th to 20th	Day	8% 13% 5% 10% 7% 6% 5% 5% 6% 7% 28%	2492
	21st to end	Day	8% 15% 5% 10% 6% 5% 5% 4 6% 7% 28%	2909
May	1st to 10th	Day	5% 12% 3 8% 4 4 4 3 5% 7% 45%	8195
	11th to 20th	Day	10% 13% 4 10% 6% 6% 6% 5% 7% 9% 25%	8160
	21st to end	Day	11% 12% 4 8% 5% 5% 5% 4 6% 8% 31%	8993
June	1st to 10th	Day	14% 10% 3 9% 6% 5% 5% 4 6% 6% 32%	3168
	11th to 20th	Day	15% 9% 3 8% 6% 5% 4 5% 6% 7% 32%	3360
	21st to end	Day	10% 7% 3 7% 6% 5% 5% 4 6% 7% 40%	3283
July	1st to 10th	Day	5% 3 1 4 3 3 4 3 6% 9% 58%	8820
	11th to 20th	Day	4 2 1 3 3 3 3 3 4 6% 68%	8581
	21st to end	Day	4 3 1 4 3 4 4 3 6% 9% 59%	8916
August	1st to 10th	Day	3 3 1 3 3 4 4 3 5% 6% 65%	6441
	11th to 20th	Day	3 4 2 6% 4 5% 5% 5% 7% 9% 50%	6233
	21st to end	Day	10% 6% 2 6% 4 4 5% 4 6% 9% 44%	6232
September	1st to 10th	Day	8% 6% 2 7% 4 4 4 3 5% 7% 51%	2520
	11th to 20th	Day	10% 8% 2 7% 5% 5% 4 4 4 6% 44%	2520
	21st to end	Day	12% 9% 2 8% 5% 5% 4 4 6% 7% 37%	2251
October	1st to 10th	Day	11% 10% 4 8% 4 4 5% 4 5% 6% 39%	3380
	11th to 20th	Day	17% 11% 4 8% 5% 4 4 4 5% 6% 32%	3312
	21st to end	Day	9% 16% 5% 11% 6% 5% 4 4 5% 6% 29%	3272
November	1st to 10th	Day	13% 16% 5% 11% 6% 6% 5% 5% 5% 6% 21%	1708
	11th to 20th	Day	11% 16% 5% 9% 7% 5% 5% 5% 6% 7% 25%	1680
	21st to end	Day	9% 17% 5% 9% 7% 5% 7% 5% 6% 8% 23%	1651
December	1st to 10th	Day	7% 13% 4 11% 6% 5% 6% 5% 7% 7% 28%	2360
	11th to 20th	Day	8% 17% 5% 13% 6% 6% 6% 5% 7% 7% 19%	2559
	21st to end	Day	6% 15% 6% 15% 10% 7% 7% 5% 7% 7% 16%	3411
January	1st to 10th	Night	8% 18% 7% 15% 8% 7% 6% 5% 6% 7% 15%	8770
	11th to 20th	Night	7% 12% 4 8% 5% 4 4 3 7% 6% 39%	8320
	21st to end	Night	6% 11% 4 11% 6% 6% 6% 5% 6% 7% 32%	8994
February	1st to 10th	Night	8% 18% 6% 14% 7% 4 6% 4 6% 6% 22%	2851
	11th to 20th	Night	5% 15% 5% 12% 7% 6% 5% 4 6% 6% 31%	2662
	21st to end	Night	5% 15% 7% 12% 9% 6% 6% 4 6% 7% 23%	2137
March	1st to 10th	Night	3 10% 4 11% 6% 6% 6% 5% 9% 10% 32%	5496
	11th to 20th	Night	3 9% 4 11% 7% 6% 6% 5% 7% 8% 35%	5246
	21st to end	Night	8% 14% 5% 10% 7% 7% 7% 5% 6% 6% 23%	5254
April	1st to 10th	Night	5% 12% 5% 10% 6% 7% 5% 6% 5% 8% 31%	2100
	11th to 20th	Night	6% 12% 4 9% 6% 5% 7% 5% 7% 8% 32%	2079
	21st to end	Night	6% 10% 4 8% 6% 6% 6% 4 6% 9% 35%	1708
May	1st to 10th	Night	5% 8% 3 6% 4 4 5% 4 6% 6% 49%	4724
	11th to 20th	Night	7% 12% 4 10% 5% 5% 5% 5% 8% 9% 32%	4700
	21st to end	Night	7% 9% 3 8% 6% 5% 6% 5% 7% 8% 36%	5178
June	1st to 10th	Night	10% 9% 2 7% 5% 5% 5% 6% 7% 9% 34%	1443
	11th to 20th	Night	9% 7% 3 7% 5% 5% 6% 4 7% 8% 38%	1260
	21st to end	Night	6% 7% 2 6% 5% 3 5% 4 7% 10% 46%	1331
July	1st to 10th	Night	3 4 1 5% 3 3 4 3 5% 7% 62%	4140
	11th to 20th	Night	2 2 1 3 2 3 3 3 4 6% 72%	4375
	21st to end	Night	3 2 1 4 3 2 3 3 5% 7% 65%	5152
August	1st to 10th	Night	2 2 1 4 3 3 4 3 5% 7% 67%	3709
	11th to 20th	Night	3 3 1 4 4 4 4 4 7% 10% 55%	3814
	21st to end	Night	7% 5% 3 8% 4 3 4 3 5% 7% 51%	4931
September	1st to 10th	Night	6% 5% 1 4 4 3 4 4 5% 7% 56%	2100
	11th to 20th	Night	8% 6% 2 6% 4 4 5% 3 6% 8% 49%	2100
	21st to end	Night	10% 10% 3 7% 4 4 4 4 6% 9% 40%	2364
October	1st to 10th	Night	9% 9% 3 8% 4 4 5% 4 6% 7% 40%	4040
	11th to 20th	Night	17% 10% 3 9% 4 4 4 4 5% 6% 34%	4063
	21st to end	Night	9% 12% 5% 10% 5% 5% 5% 3 5% 5% 34%	4704
November	1st to 10th	Night	13% 15% 4 11% 5% 5% 5% 5% 6% 7% 25%	2807
	11th to 20th	Night	9% 15% 5% 11% 7% 6% 5% 5% 6% 6% 25%	2940
	21st to end	Night	8% 16% 5% 11% 6% 6% 5% 5% 6% 6% 24%	2945
December	1st to 10th	Night	7% 13% 3 8% 5% 5% 5% 5% 6% 7% 35%	5040
	11th to 20th	Night	7% 18% 7% 15% 7% 6% 6% 4 5% 6% 19%	5823
	21st to end	Night	5% 14% 6% 15% 7% 7% 7% 5% 7% 7% 20%	7829

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	68% 6% 10% 13% 3	4125
	11th to 20th	Day	45% 4 17% 24% 7% 3	4598
	21st to end	Day	54% 7% 13% 17% 8%	5187
February	1st to 10th	Day	60% 10% 11% 9% 8% 1	1768
	11th to 20th	Day	58% 10% 12% 12% 7% 1	1854
	21st to end	Day	64% 10% 9% 12% 6%	1668
March	1st to 10th	Day	54% 7% 11% 15% 13%	4618
	11th to 20th	Day	52% 7% 12% 20% 9%	4970
	21st to end	Day	60% 8% 11% 13% 8%	5962
April	1st to 10th	Day	58% 11% 13% 15% 3	2520
	11th to 20th	Day	54% 9% 11% 16% 9% 1	2492
	21st to end	Day	54% 9% 13% 14% 9% 1	2909
May	1st to 10th	Day	39% 6% 10% 33% 12% 1	8195
	11th to 20th	Day	53% 7% 16% 20% 4	8163
	21st to end	Day	50% 6% 15% 25% 4	8994
June	1st to 10th	Day	52% 8% 12% 17% 9% 3	3168
	11th to 20th	Day	51% 10% 12% 19% 9%	3360
	21st to end	Day	43% 9% 15% 21% 12% 1	3283
July	1st to 10th	Day	25% 2 12% 25% 24% 11%	8746
	11th to 20th	Day	20% 2 11% 25% 31% 11%	8500
	21st to end	Day	24% 2 15% 33% 20% 6%	8723
August	1st to 10th	Day	21% 3 9% 26% 32% 9%	6424
	11th to 20th	Day	31% 3 23% 33% 9% 2	6275
	21st to end	Day	38% 5% 18% 27% 11% 1	6231
September	1st to 10th	Day	34% 5% 15% 26% 16% 4	2520
	11th to 20th	Day	42% 6% 11% 23% 16% 3	2520
	21st to end	Day	45% 7% 18% 18% 9% 2	2251
October	1st to 10th	Day	47% 5% 15% 27% 6%	3380
	11th to 20th	Day	54% 5% 9% 25% 7% 1	3312
	21st to end	Day	56% 6% 14% 18% 5%	3272
November	1st to 10th	Day	63% 10% 12% 11% 4	1708
	11th to 20th	Day	59% 8% 13% 14% 5% 1	1680
	21st to end	Day	58% 10% 13% 14% 5% 2	1651
December	1st to 10th	Day	53% 8% 21% 12% 5%	2360
	11th to 20th	Day	62% 8% 15% 11% 4	2560
	21st to end	Day	64% 9% 13% 12% 2	3411
January	1st to 10th	Night	67% 7% 12% 11% 2	8770
	11th to 20th	Night	45% 5% 15% 23% 9% 3	8358
	21st to end	Night	50% 9% 15% 18% 10%	8994
February	1st to 10th	Night	62% 8% 11% 12% 6% 1	2851
	11th to 20th	Night	54% 9% 12% 15% 8% 2	2664
	21st to end	Night	60% 8% 11% 14% 7%	2137
March	1st to 10th	Night	42% 9% 15% 22% 12%	5496
	11th to 20th	Night	44% 8% 15% 24% 9%	5247
	21st to end	Night	57% 8% 12% 15% 7%	5254
April	1st to 10th	Night	48% 11% 20% 17% 4	2100
	11th to 20th	Night	48% 10% 16% 18% 8%	2079
	21st to end	Night	44% 9% 19% 19% 9%	1708
May	1st to 10th	Night	33% 5% 14% 36% 11%	4721
	11th to 20th	Night	46% 8% 20% 22% 3	4700
	21st to end	Night	42% 9% 19% 25% 4	5182
June	1st to 10th	Night	44% 9% 16% 20% 9% 2	1443
	11th to 20th	Night	41% 11% 17% 21% 10%	1260
	21st to end	Night	32% 10% 23% 23% 11% 1	1331
July	1st to 10th	Night	23% 3 17% 29% 18% 10%	4105
	11th to 20th	Night	16% 2 16% 28% 32% 6%	4333
	21st to end	Night	21% 1 19% 34% 17% 8%	5040
August	1st to 10th	Night	19% 3 11% 27% 31% 8%	3701
	11th to 20th	Night	24% 3 29% 34% 8% 2	3838
	21st to end	Night	34% 5% 22% 26% 11% 2	4931
September	1st to 10th	Night	27% 7% 16% 31% 16% 3	2100
	11th to 20th	Night	32% 9% 14% 23% 18% 4	2100
	21st to end	Night	42% 8% 17% 21% 10% 2	2364
October	1st to 10th	Night	44% 5% 18% 27% 7%	4040
	11th to 20th	Night	52% 4 11% 23% 10%	4063
	21st to end	Night	52% 5% 14% 23% 6%	4704
November	1st to 10th	Night	59% 9% 13% 12% 6% 1	2807
	11th to 20th	Night	58% 9% 14% 13% 5% 1	2940
	21st to end	Night	57% 11% 14% 11% 6% 1	2945
December	1st to 10th	Night	48% 8% 17% 22% 5% 1	5040
	11th to 20th	Night	66% 7% 12% 12% 2	5820
	21st to end	Night	59% 10% 12% 15% 4	7829

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	20% 24% 27% 15% 10% 5%	220
	11th to 20th	Day	14% 18% 33% 21% 13% 1	220
	21st to end	Day	14% 22% 31% 22% 10%	242
February	1st to 10th	Day	27% 22% 28% 17% 6% 1	308
	11th to 20th	Day	17% 22% 35% 18% 7% 2	425
	21st to end	Day	25% 22% 32% 15% 5%	414
March	1st to 10th	Day	24% 23% 27% 19% 7% 1	540
	11th to 20th	Day	24% 25% 24% 16% 9% 3	540
	21st to end	Day	25% 27% 22% 16% 9% 1	594
April	1st to 10th	Day	24% 25% 27% 16% 6% 2	540
	11th to 20th	Day	20% 24% 25% 19% 9% 3	532
	21st to end	Day	23% 23% 25% 19% 8% 3	540
May	1st to 10th	Day	16% 18% 35% 20% 8% 2	543
	11th to 20th	Day	20% 16% 25% 26% 11% 2	568
	21st to end	Day	23% 18% 26% 20% 10% 3	617
June	1st to 10th	Day	21% 21% 31% 18% 9% 1	798
	11th to 20th	Day	21% 20% 29% 19% 9% 2	990
	21st to end	Day	17% 14% 29% 23% 14% 3	913
July	1st to 10th	Day	12% 16% 34% 25% 11% 1	771
	11th to 20th	Day	9% 17% 32% 27% 12% 2	685
	21st to end	Day	8% 11% 32% 31% 16% 3	619
August	1st to 10th	Day	8% 10% 27% 31% 18% 6%	567
	11th to 20th	Day	8% 10% 31% 29% 17% 6%	557
	21st to end	Day	12% 13% 30% 26% 13% 5%	627
September	1st to 10th	Day	12% 14% 29% 23% 17% 6%	570
	11th to 20th	Day	15% 14% 28% 25% 14% 4	570
	21st to end	Day	24% 19% 27% 18% 9% 3	570
October	1st to 10th	Day	22% 17% 27% 17% 13% 4	570
	11th to 20th	Day	27% 19% 23% 17% 12% 2	546
	21st to end	Day	28% 16% 26% 19% 8% 2	387
November	1st to 10th	Day	26% 21% 29% 19% 4 1	253
	11th to 20th	Day	30% 19% 25% 12% 12% 3	220
	21st to end	Day	23% 19% 29% 17% 8% 4	220
December	1st to 10th	Day	24% 13% 24% 21% 12% 7%	220
	11th to 20th	Day	25% 22% 25% 15% 9% 4	220
	21st to end	Day	20% 16% 33% 21% 6% 3	242
January	1st to 10th	Night	24% 18% 30% 18% 9% 1	950
	11th to 20th	Night	16% 16% 31% 27% 9% 1	865
	21st to end	Night	15% 15% 32% 26% 10% 2	924
February	1st to 10th	Night	21% 18% 28% 23% 8% 2	840
	11th to 20th	Night	13% 16% 31% 28% 11% 1	824
	21st to end	Night	16% 19% 26% 24% 14% 1	692
March	1st to 10th	Night	15% 21% 25% 24% 13% 2	840
	11th to 20th	Night	15% 21% 32% 21% 9% 2	840
	21st to end	Night	16% 19% 29% 23% 11% 2	924
April	1st to 10th	Night	14% 17% 27% 29% 11% 2	840
	11th to 20th	Night	13% 17% 29% 27% 13% 1	831
	21st to end	Night	12% 15% 30% 30% 11% 2	448
May	1st to 10th	Night	13% 10% 30% 31% 14% 2	420
	11th to 20th	Night	12% 8% 28% 34% 17% 1	414
	21st to end	Night	16% 9% 27% 31% 15% 2	455
June	1st to 10th	Night	14% 13% 33% 28% 11% 1	420
	11th to 20th	Night	14% 15% 32% 28% 11%	420
	21st to end	Night	8% 10% 32% 31% 18% 1	420
July	1st to 10th	Night	7% 9% 27% 37% 19% 1	410
	11th to 20th	Night	6% 10% 31% 35% 17% 1	408
	21st to end	Night	4 7% 29% 38% 21% 2	460
August	1st to 10th	Night	5% 5% 22% 39% 25% 3	418
	11th to 20th	Night	5% 4 24% 35% 27% 5%	475
	21st to end	Night	10% 8% 25% 33% 22% 2	850
September	1st to 10th	Night	9% 9% 26% 30% 23% 4	840
	11th to 20th	Night	12% 8% 23% 25% 25% 6%	840
	21st to end	Night	18% 14% 27% 22% 16% 3	840
October	1st to 10th	Night	15% 11% 28% 27% 17% 3	840
	11th to 20th	Night	21% 15% 23% 24% 14% 2	840
	21st to end	Night	20% 20% 25% 22% 10% 2	912
November	1st to 10th	Night	24% 18% 30% 22% 6% 1	820
	11th to 20th	Night	22% 21% 28% 19% 8% 1	840
	21st to end	Night	18% 20% 27% 22% 10% 2	845
December	1st to 10th	Night	17% 15% 29% 26% 11% 2	1050
	11th to 20th	Night	21% 20% 30% 21% 7% 1	1080
	21st to end	Night	18% 22% 31% 23% 7%	1134

Page generated at 2026-10-26 01:37:50. Version ac07

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