Caresland
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caresland clear sky chart from 2005-11-06 to 2025-07-06.

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	8% 8% 3 8% 5% 5% 5% 4 6% 8% 40%	123754
	Night	6% 10% 4 9% 5% 5% 5% 4 6% 8% 37%	123729
Transparency	Day	40% 6% 14% 25% 12% 2	123498
	Night	43% 7% 14% 23% 12% 2	123628
Seeing	Day	12% 7% 25% 30% 19% 6%	16236
	Night	11% 6% 30% 35% 15% 2	25348

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	3 10% 7% 15% 8% 7% 5% 4 6% 6% 30%	3179
	11th to 20th	Day	3 9% 4 11% 6% 5% 5% 6% 8% 6% 37%	3187
	21st to end	Day	3 7% 3 9% 6% 5% 5% 4 6% 7% 46%	4004
February	1st to 10th	Day	4 11% 5% 13% 7% 7% 7% 3 5% 8% 27%	1619
	11th to 20th	Day	6% 12% 5% 10% 6% 7% 6% 6% 8% 8% 27%	1755
	21st to end	Day	3 13% 6% 10% 6% 6% 5% 3 8% 8% 31%	1587
March	1st to 10th	Day	3 10% 5% 12% 6% 5% 4 4 5% 10% 37%	4518
	11th to 20th	Day	5% 9% 4 8% 5% 5% 5% 4 6% 8% 40%	4990
	21st to end	Day	8% 18% 6% 13% 5% 5% 5% 4 6% 7% 22%	5517
April	1st to 10th	Day	8% 13% 4 10% 6% 5% 4 5% 7% 7% 30%	2470
	11th to 20th	Day	10% 12% 3 9% 6% 5% 6% 4 7% 7% 31%	2570
	21st to end	Day	12% 12% 3 9% 6% 4 5% 5% 5% 7% 32%	2600
May	1st to 10th	Day	15% 10% 3 6% 4 4 4 4 5% 6% 39%	6146
	11th to 20th	Day	11% 9% 4 10% 6% 6% 6% 5% 7% 9% 27%	6734
	21st to end	Day	11% 7% 3 8% 5% 5% 6% 5% 6% 7% 38%	7405
June	1st to 10th	Day	14% 8% 2 6% 6% 6% 6% 5% 7% 8% 33%	3000
	11th to 20th	Day	18% 8% 3 6% 5% 5% 6% 6% 6% 7% 30%	3000
	21st to end	Day	8% 5% 2 5% 5% 4 5% 5% 8% 10% 43%	3000
July	1st to 10th	Day	6% 4 2 5% 4 5% 5% 4 7% 9% 51%	4816
	11th to 20th	Day	6% 3 1 4 3 4 4 4 6% 10% 54%	4740
	21st to end	Day	3 3 1 3 3 3 4 4 6% 9% 62%	5050
August	1st to 10th	Day	8% 6% 2 6% 4 4 5% 5% 7% 9% 43%	4401
	11th to 20th	Day	6% 5% 2 6% 4 4 5% 4 7% 10% 48%	4030
	21st to end	Day	10% 3 1 4 3 3 4 4 5% 8% 55%	4521
September	1st to 10th	Day	9% 6% 2 6% 4 4 4 3 5% 6% 51%	2359
	11th to 20th	Day	15% 8% 3 5% 3 4 4 3 5% 7% 44%	2090
	21st to end	Day	9% 7% 2 6% 4 4 4 3 5% 8% 46%	2090
October	1st to 10th	Day	7% 6% 3 7% 5% 5% 5% 5% 7% 8% 43%	3316
	11th to 20th	Day	6% 7% 2 7% 4 5% 5% 4 6% 9% 46%	2950
	21st to end	Day	6% 8% 3 7% 4 5% 6% 4 5% 7% 45%	3101
November	1st to 10th	Day	9% 16% 5% 8% 5% 5% 5% 4 5% 7% 31%	1620
	11th to 20th	Day	7% 10% 3 10% 6% 5% 5% 3 5% 8% 38%	1559
	21st to end	Day	4 11% 6% 8% 6% 5% 6% 4 8% 10% 32%	1400
December	1st to 10th	Day	4 13% 5% 12% 6% 5% 6% 4 5% 7% 34%	2290
	11th to 20th	Day	4 10% 5% 12% 7% 6% 5% 4 7% 6% 33%	2642
	21st to end	Day	3 10% 3 7% 5% 4 6% 4 6% 9% 42%	3498
January	1st to 10th	Night	3 15% 5% 14% 8% 7% 5% 4 5% 7% 25%	6766
	11th to 20th	Night	3 10% 5% 12% 6% 6% 6% 5% 6% 7% 34%	6739
	21st to end	Night	3 10% 5% 9% 5% 4 4 4 6% 7% 43%	6952
February	1st to 10th	Night	4 12% 4 12% 6% 7% 6% 5% 5% 8% 30%	2780
	11th to 20th	Night	5% 13% 4 11% 6% 5% 6% 5% 7% 8% 29%	2532
	21st to end	Night	3 11% 5% 12% 8% 6% 5% 3 7% 8% 33%	2040
March	1st to 10th	Night	3 8% 4 12% 7% 6% 5% 5% 7% 10% 33%	5376
	11th to 20th	Night	5% 9% 4 10% 5% 5% 5% 4 6% 8% 37%	5008
	21st to end	Night	9% 19% 6% 12% 6% 5% 5% 5% 6% 7% 20%	5456
April	1st to 10th	Night	8% 14% 4 11% 5% 5% 5% 4 6% 8% 30%	1930
	11th to 20th	Night	9% 13% 4 10% 6% 6% 4 4 6% 7% 32%	1781
	21st to end	Night	9% 12% 4 9% 6% 5% 5% 5% 6% 9% 32%	1800
May	1st to 10th	Night	15% 10% 3 8% 4 5% 4 4 5% 6% 35%	3824
	11th to 20th	Night	13% 9% 3 9% 5% 6% 5% 5% 7% 9% 29%	3159
	21st to end	Night	11% 7% 3 8% 5% 5% 5% 4 6% 7% 38%	3470
June	1st to 10th	Night	13% 8% 3 7% 6% 5% 6% 6% 5% 7% 33%	1400
	11th to 20th	Night	16% 7% 2 8% 5% 5% 6% 5% 6% 8% 31%	1400
	21st to end	Night	8% 4 2 6% 4 5% 5% 5% 7% 8% 46%	1400
July	1st to 10th	Night	6% 4 2 6% 5% 5% 6% 5% 6% 8% 48%	2255
	11th to 20th	Night	4 3 1 4 3 4 4 4 9% 13% 50%	2220
	21st to end	Night	4 4 1 5% 3 3 4 3 7% 8% 58%	2500
August	1st to 10th	Night	9% 6% 2 7% 4 5% 5% 5% 7% 9% 42%	2529
	11th to 20th	Night	6% 4 2 7% 5% 4 5% 5% 8% 11% 43%	2808
	21st to end	Night	8% 3 2 3 3 3 4 4 6% 9% 54%	3146
September	1st to 10th	Night	10% 5% 3 6% 4 3 4 4 6% 7% 48%	1818
	11th to 20th	Night	13% 7% 2 5% 3 3 4 3 5% 7% 49%	2090
	21st to end	Night	8% 6% 2 5% 4 4 4 4 7% 8% 47%	2090
October	1st to 10th	Night	7% 6% 2 5% 4 4 4 4 6% 8% 50%	3645
	11th to 20th	Night	6% 7% 2 6% 4 4 4 4 6% 8% 48%	3962
	21st to end	Night	5% 8% 2 7% 4 5% 5% 5% 7% 7% 44%	4457
November	1st to 10th	Night	8% 15% 3 8% 5% 4 5% 4 6% 8% 34%	2658
	11th to 20th	Night	5% 11% 3 8% 6% 5% 5% 5% 8% 7% 37%	2840
	21st to end	Night	5% 11% 3 9% 5% 5% 5% 4 7% 9% 37%	3000
December	1st to 10th	Night	3 12% 4 10% 6% 7% 7% 5% 7% 8% 31%	4890
	11th to 20th	Night	4 11% 5% 13% 7% 6% 6% 5% 7% 8% 28%	5550
	21st to end	Night	4 9% 4 9% 5% 5% 5% 4 6% 7% 42%	7458

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	53% 6% 11% 20% 8% 1	3179
	11th to 20th	Day	44% 5% 13% 16% 18% 3	3208
	21st to end	Day	36% 6% 13% 31% 13% 1	4004
February	1st to 10th	Day	54% 7% 14% 15% 9% 2	1619
	11th to 20th	Day	50% 8% 13% 19% 9% 1	1764
	21st to end	Day	49% 6% 12% 20% 12% 1	1587
March	1st to 10th	Day	43% 4 13% 22% 16% 1	4518
	11th to 20th	Day	39% 5% 15% 23% 17% 1	4991
	21st to end	Day	60% 6% 14% 14% 6%	5517
April	1st to 10th	Day	50% 7% 14% 19% 10% 1	2470
	11th to 20th	Day	49% 6% 12% 22% 10% 2	2570
	21st to end	Day	49% 6% 13% 21% 10% 1	2600
May	1st to 10th	Day	44% 6% 9% 22% 15% 5%	6146
	11th to 20th	Day	48% 9% 14% 22% 7%	6738
	21st to end	Day	42% 7% 15% 26% 10% 1	7406
June	1st to 10th	Day	45% 8% 14% 22% 9% 2	3000
	11th to 20th	Day	49% 8% 14% 19% 8% 2	3000
	21st to end	Day	33% 9% 19% 27% 10% 2	3000
July	1st to 10th	Day	27% 7% 17% 29% 17% 3	4742
	11th to 20th	Day	24% 7% 19% 34% 14% 1	4659
	21st to end	Day	18% 6% 12% 30% 25% 9%	4890
August	1st to 10th	Day	34% 8% 15% 35% 8% 1	4384
	11th to 20th	Day	30% 7% 22% 31% 8% 2	4069
	21st to end	Day	27% 6% 18% 35% 14% 1	4520
September	1st to 10th	Day	32% 6% 14% 27% 15% 6%	2359
	11th to 20th	Day	39% 6% 14% 27% 12% 2	2090
	21st to end	Day	36% 6% 14% 29% 12% 3	2090
October	1st to 10th	Day	37% 6% 17% 31% 8% 1	3316
	11th to 20th	Day	33% 6% 18% 28% 13% 3	2950
	21st to end	Day	38% 5% 10% 33% 12% 1	3101
November	1st to 10th	Day	51% 8% 11% 20% 9% 2	1620
	11th to 20th	Day	45% 6% 14% 24% 10% 1	1559
	21st to end	Day	45% 7% 16% 22% 9% 2	1400
December	1st to 10th	Day	50% 6% 13% 23% 7% 2	2290
	11th to 20th	Day	49% 6% 18% 21% 6% 1	2644
	21st to end	Day	37% 6% 12% 25% 18% 4	3498
January	1st to 10th	Night	56% 5% 12% 20% 5% 1	6766
	11th to 20th	Night	47% 6% 13% 17% 14% 3	6780
	21st to end	Night	39% 5% 14% 28% 13% 1	6952
February	1st to 10th	Night	50% 6% 13% 18% 12% 2	2780
	11th to 20th	Night	49% 7% 12% 19% 11% 1	2533
	21st to end	Night	47% 5% 13% 21% 11% 2	2040
March	1st to 10th	Night	43% 6% 18% 20% 11% 1	5376
	11th to 20th	Night	42% 7% 15% 23% 12% 1	5008
	21st to end	Night	61% 7% 12% 12% 8% 1	5456
April	1st to 10th	Night	49% 6% 14% 19% 13%	1930
	11th to 20th	Night	50% 7% 11% 21% 10% 1	1781
	21st to end	Night	47% 7% 14% 21% 10% 2	1800
May	1st to 10th	Night	49% 6% 8% 21% 15% 2	3821
	11th to 20th	Night	47% 8% 14% 23% 7% 1	3159
	21st to end	Night	42% 8% 16% 23% 9% 1	3470
June	1st to 10th	Night	48% 9% 13% 19% 11% 1	1400
	11th to 20th	Night	47% 9% 16% 19% 8% 2	1400
	21st to end	Night	33% 10% 20% 27% 10% 1	1400
July	1st to 10th	Night	31% 8% 16% 25% 18% 2	2220
	11th to 20th	Night	23% 10% 20% 34% 10% 3	2178
	21st to end	Night	22% 7% 11% 30% 22% 7%	2421
August	1st to 10th	Night	35% 9% 13% 28% 14% 1	2521
	11th to 20th	Night	31% 10% 22% 27% 9% 1	2835
	21st to end	Night	25% 6% 19% 34% 13% 3	3146
September	1st to 10th	Night	33% 6% 15% 25% 15% 6%	1818
	11th to 20th	Night	36% 7% 13% 26% 13% 5%	2090
	21st to end	Night	32% 5% 18% 26% 14% 4	2090
October	1st to 10th	Night	31% 6% 15% 28% 18% 2	3645
	11th to 20th	Night	33% 6% 17% 25% 16% 2	3962
	21st to end	Night	36% 6% 12% 32% 13% 1	4457
November	1st to 10th	Night	48% 7% 11% 21% 11% 2	2658
	11th to 20th	Night	43% 8% 15% 20% 13% 1	2840
	21st to end	Night	43% 9% 16% 20% 10% 3	3000
December	1st to 10th	Night	49% 8% 16% 19% 7% 2	4890
	11th to 20th	Night	51% 7% 19% 18% 5%	5547
	21st to end	Night	40% 4 10% 26% 17% 3	7458

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	8% 5% 32% 32% 14% 11%	200
	11th to 20th	Day	6% 7% 33% 34% 15% 6%	200
	21st to end	Day	8% 9% 29% 35% 15% 4	220
February	1st to 10th	Day	10% 9% 27% 38% 12% 4	210
	11th to 20th	Day	8% 7% 33% 34% 15% 3	300
	21st to end	Day	7% 9% 31% 34% 16% 3	351
March	1st to 10th	Day	9% 10% 33% 29% 13% 5%	500
	11th to 20th	Day	7% 11% 32% 33% 13% 4	500
	21st to end	Day	13% 13% 32% 22% 15% 5%	550
April	1st to 10th	Day	12% 11% 31% 30% 12% 4	500
	11th to 20th	Day	14% 11% 28% 28% 15% 4	492
	21st to end	Day	18% 11% 25% 27% 15% 5%	500
May	1st to 10th	Day	17% 9% 23% 23% 21% 6%	561
	11th to 20th	Day	14% 6% 21% 32% 22% 6%	725
	21st to end	Day	17% 4 20% 28% 23% 7%	789
June	1st to 10th	Day	15% 8% 24% 31% 18% 4	730
	11th to 20th	Day	18% 7% 25% 29% 17% 3	730
	21st to end	Day	9% 4 23% 32% 24% 8%	730
July	1st to 10th	Day	9% 4 18% 33% 28% 8%	697
	11th to 20th	Day	11% 4 19% 32% 25% 8%	668
	21st to end	Day	6% 5% 21% 32% 27% 9%	687
August	1st to 10th	Day	9% 5% 22% 33% 23% 9%	487
	11th to 20th	Day	8% 2 21% 31% 29% 9%	477
	21st to end	Day	12% 6% 19% 32% 19% 12%	539
September	1st to 10th	Day	12% 6% 25% 30% 20% 7%	490
	11th to 20th	Day	18% 7% 21% 28% 20% 6%	490
	21st to end	Day	13% 12% 26% 31% 14% 4	490
October	1st to 10th	Day	17% 8% 19% 29% 20% 6%	394
	11th to 20th	Day	9% 8% 32% 26% 17% 7%	300
	21st to end	Day	14% 12% 33% 26% 12% 3	330
November	1st to 10th	Day	18% 8% 30% 27% 14% 3	300
	11th to 20th	Day	13% 10% 39% 25% 11% 2	279
	21st to end	Day	10% 8% 32% 28% 13% 10%	200
December	1st to 10th	Day	7% 9% 36% 30% 15% 5%	200
	11th to 20th	Day	9% 10% 38% 30% 12% 2	200
	21st to end	Day	9% 4 25% 33% 25% 4	220
January	1st to 10th	Night	8% 9% 34% 35% 12% 2	1000
	11th to 20th	Night	9% 6% 37% 33% 13% 2	1000
	21st to end	Night	11% 10% 34% 32% 12% 1	880
February	1st to 10th	Night	9% 8% 29% 36% 15% 2	800
	11th to 20th	Night	11% 6% 31% 38% 13% 1	784
	21st to end	Night	6% 5% 30% 35% 19% 4	660
March	1st to 10th	Night	9% 5% 32% 35% 16% 3	800
	11th to 20th	Night	9% 7% 35% 35% 13% 1	800
	21st to end	Night	14% 7% 29% 34% 13% 3	880
April	1st to 10th	Night	13% 6% 31% 34% 13% 2	730
	11th to 20th	Night	15% 8% 31% 34% 12%	593
	21st to end	Night	15% 8% 30% 35% 12% 1	600
May	1st to 10th	Night	18% 5% 26% 34% 16% 1	540
	11th to 20th	Night	13% 4 24% 36% 21% 1	394
	21st to end	Night	18% 5% 20% 38% 18% 2	433
June	1st to 10th	Night	17% 8% 24% 38% 13% 2	400
	11th to 20th	Night	17% 4 30% 33% 15% 1	400
	21st to end	Night	11% 3 21% 42% 22% 2	400
July	1st to 10th	Night	9% 5% 14% 45% 26% 1	380
	11th to 20th	Night	9% 2 21% 44% 22% 2	368
	21st to end	Night	6% 1 22% 44% 26% 1	416
August	1st to 10th	Night	11% 3 16% 40% 29% 2	378
	11th to 20th	Night	9% 4 18% 45% 24% 2	561
	21st to end	Night	10% 5% 20% 40% 24% 1	627
September	1st to 10th	Night	13% 4 21% 40% 20% 2	645
	11th to 20th	Night	17% 4 18% 38% 22% 2	760
	21st to end	Night	11% 5% 31% 35% 16% 2	760
October	1st to 10th	Night	16% 4 24% 37% 18% 2	760
	11th to 20th	Night	11% 6% 33% 33% 15% 3	760
	21st to end	Night	11% 7% 34% 34% 13% 1	836
November	1st to 10th	Night	15% 7% 38% 31% 9% 1	903
	11th to 20th	Night	10% 10% 40% 29% 9% 2	1000
	21st to end	Night	10% 6% 37% 34% 10% 3	1000
December	1st to 10th	Night	10% 7% 32% 34% 15% 2	1000
	11th to 20th	Night	9% 7% 37% 35% 11% 1	1000
	21st to end	Night	12% 5% 33% 33% 14% 3	1100

Page generated at 2025-07-02 23:30:18. Version ac07

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