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 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	8% 8% 3 7% 5% 5% 5% 4 6% 8% 41%	154480
	Night	6% 9% 3 9% 5% 5% 5% 4 6% 8% 39%	146328
Transparency	Day	39% 6% 15% 26% 12% 2	154180
	Night	41% 6% 15% 23% 12% 2	146211
Seeing	Day	12% 8% 26% 30% 19% 6%	18013
	Night	11% 6% 30% 36% 15% 2	26998

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% 6% 14% 8% 7% 5% 4 6% 7% 29%	4125
	11th to 20th	Day	3 8% 4 10% 6% 5% 5% 5% 7% 6% 41%	4161
	21st to end	Day	2 7% 3 10% 5% 5% 4 4 6% 8% 46%	5186
February	1st to 10th	Day	4 11% 5% 13% 7% 7% 8% 4 6% 8% 27%	1700
	11th to 20th	Day	6% 12% 5% 10% 6% 6% 6% 6% 8% 8% 28%	1845
	21st to end	Day	3 12% 6% 10% 6% 6% 5% 4 7% 8% 31%	1664
March	1st to 10th	Day	3 10% 5% 12% 6% 5% 4 4 5% 10% 37%	4618
	11th to 20th	Day	5% 9% 4 8% 5% 5% 6% 4 6% 8% 40%	5100
	21st to end	Day	8% 18% 6% 13% 5% 5% 5% 4 6% 7% 22%	5638
April	1st to 10th	Day	9% 13% 4 10% 6% 5% 4 5% 7% 7% 30%	2594
	11th to 20th	Day	10% 12% 3 8% 6% 5% 6% 4 7% 8% 31%	2700
	21st to end	Day	12% 12% 3 8% 6% 5% 5% 5% 5% 8% 32%	2730
May	1st to 10th	Day	12% 9% 3 6% 4 4 5% 4 6% 7% 40%	7970
	11th to 20th	Day	11% 9% 4 9% 6% 6% 7% 5% 8% 9% 27%	8755
	21st to end	Day	11% 6% 2 7% 5% 5% 6% 5% 7% 8% 37%	9649
June	1st to 10th	Day	15% 8% 2 6% 6% 5% 6% 5% 7% 8% 33%	3150
	11th to 20th	Day	17% 8% 3 6% 5% 6% 6% 6% 6% 7% 30%	3150
	21st to end	Day	9% 5% 2 5% 5% 4 5% 5% 8% 10% 43%	3150
July	1st to 10th	Day	6% 4 1 4 3 4 4 4 6% 9% 53%	8820
	11th to 20th	Day	9% 4 1 4 3 4 4 4 6% 10% 50%	8820
	21st to end	Day	6% 4 1 4 3 3 3 3 5% 7% 61%	9397
August	1st to 10th	Day	7% 5% 2 5% 4 4 5% 4 6% 9% 49%	6441
	11th to 20th	Day	11% 5% 2 5% 4 3 5% 4 6% 9% 46%	5927
	21st to end	Day	7% 3 1 4 3 3 4 4 5% 7% 58%	6570
September	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 5% 6% 50%	2607
	11th to 20th	Day	14% 7% 2 5% 3 4 4 3 5% 7% 46%	2310
	21st to end	Day	8% 7% 2 6% 4 4 4 3 6% 8% 47%	2310
October	1st to 10th	Day	7% 6% 2 6% 5% 4 5% 5% 7% 8% 44%	3526
	11th to 20th	Day	6% 7% 2 7% 4 5% 5% 4 6% 9% 46%	3138
	21st to end	Day	6% 8% 3 7% 4 5% 6% 4 5% 7% 45%	3272
November	1st to 10th	Day	9% 16% 4 8% 5% 5% 5% 4 5% 7% 31%	1703
	11th to 20th	Day	7% 11% 3 10% 6% 4 5% 3 5% 8% 39%	1637
	21st to end	Day	4 11% 6% 9% 6% 5% 6% 4 8% 10% 31%	1470
December	1st to 10th	Day	4 13% 5% 12% 6% 5% 6% 4 5% 7% 33%	2360
	11th to 20th	Day	4 10% 5% 12% 7% 6% 5% 4 7% 7% 33%	2712
	21st to end	Day	3 10% 3 7% 5% 4 6% 4 6% 9% 42%	3575
January	1st to 10th	Night	4 13% 5% 13% 7% 6% 5% 4 6% 8% 28%	8768
	11th to 20th	Night	2 8% 5% 10% 6% 6% 6% 4 6% 8% 39%	8779
	21st to end	Night	2 8% 5% 10% 6% 5% 5% 4 6% 7% 41%	8994
February	1st to 10th	Night	4 11% 4 12% 7% 7% 6% 5% 5% 9% 30%	2919
	11th to 20th	Night	5% 13% 4 11% 6% 5% 6% 5% 7% 8% 29%	2662
	21st to end	Night	3 11% 5% 11% 7% 6% 5% 3 7% 8% 34%	2139
March	1st to 10th	Night	3 8% 4 12% 7% 6% 5% 4 7% 10% 33%	5496
	11th to 20th	Night	5% 9% 4 10% 6% 5% 5% 4 6% 8% 37%	5118
	21st to end	Night	9% 19% 6% 12% 6% 5% 5% 5% 6% 7% 20%	5577
April	1st to 10th	Night	8% 14% 4 11% 5% 5% 5% 4 6% 8% 30%	2026
	11th to 20th	Night	9% 13% 4 9% 6% 6% 4 4 6% 7% 33%	1871
	21st to end	Night	9% 12% 4 9% 6% 4 5% 5% 6% 9% 32%	1890
May	1st to 10th	Night	14% 10% 3 8% 5% 5% 5% 4 5% 7% 37%	4966
	11th to 20th	Night	12% 9% 3 8% 5% 6% 5% 5% 7% 10% 30%	4105
	21st to end	Night	10% 7% 3 8% 6% 6% 5% 5% 7% 8% 35%	4522
June	1st to 10th	Night	14% 8% 3 7% 6% 5% 6% 6% 5% 8% 32%	1470
	11th to 20th	Night	15% 6% 2 8% 5% 5% 6% 5% 7% 8% 31%	1470
	21st to end	Night	8% 4 2 6% 4 5% 5% 5% 7% 8% 45%	1470
July	1st to 10th	Night	5% 3 2 5% 4 4 5% 4 7% 8% 53%	4140
	11th to 20th	Night	6% 4 2 4 3 4 4 4 7% 10% 52%	4140
	21st to end	Night	8% 4 1 5% 3 3 4 3 5% 7% 58%	4669
August	1st to 10th	Night	8% 6% 2 6% 4 4 5% 4 6% 8% 47%	3709
	11th to 20th	Night	11% 5% 2 8% 5% 4 5% 5% 8% 10% 37%	4138
	21st to end	Night	6% 3 1 3 3 4 4 4 7% 10% 54%	4578
September	1st to 10th	Night	10% 5% 3 6% 4 3 4 4 6% 8% 48%	2010
	11th to 20th	Night	13% 6% 2 5% 3 2 4 3 5% 7% 49%	2310
	21st to end	Night	8% 6% 2 5% 4 4 4 4 6% 8% 49%	2310
October	1st to 10th	Night	7% 6% 2 5% 4 4 4 4 6% 8% 50%	3875
	11th to 20th	Night	6% 7% 2 6% 4 4 4 4 6% 8% 48%	4214
	21st to end	Night	5% 8% 2 7% 4 5% 5% 5% 7% 7% 45%	4704
November	1st to 10th	Night	8% 15% 3 8% 5% 4 5% 4 6% 8% 34%	2794
	11th to 20th	Night	4 11% 3 8% 6% 5% 5% 5% 8% 8% 37%	2982
	21st to end	Night	5% 11% 3 8% 5% 4 5% 4 7% 9% 37%	3150
December	1st to 10th	Night	3 12% 4 10% 6% 7% 7% 5% 7% 8% 30%	5040
	11th to 20th	Night	4 11% 5% 13% 7% 6% 6% 5% 7% 8% 28%	5700
	21st to end	Night	4 9% 4 9% 5% 5% 5% 4 6% 7% 42%	7623

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	51% 6% 12% 20% 11% 1	4125
	11th to 20th	Day	39% 5% 16% 19% 17% 4	4182
	21st to end	Day	36% 6% 14% 31% 12% 1	5187
February	1st to 10th	Day	53% 7% 13% 15% 10% 2	1700
	11th to 20th	Day	49% 8% 13% 19% 11% 1	1854
	21st to end	Day	48% 6% 13% 21% 11% 1	1664
March	1st to 10th	Day	43% 4 13% 23% 16% 1	4618
	11th to 20th	Day	40% 6% 15% 23% 17% 1	5101
	21st to end	Day	60% 6% 14% 14% 6%	5638
April	1st to 10th	Day	49% 7% 14% 19% 9% 1	2594
	11th to 20th	Day	49% 6% 12% 22% 9% 2	2700
	21st to end	Day	49% 6% 13% 22% 10% 1	2730
May	1st to 10th	Day	42% 6% 10% 26% 14% 4	7970
	11th to 20th	Day	47% 8% 13% 23% 7% 1	8759
	21st to end	Day	41% 7% 15% 28% 9% 1	9650
June	1st to 10th	Day	46% 8% 14% 21% 9% 2	3150
	11th to 20th	Day	48% 8% 14% 20% 7% 2	3150
	21st to end	Day	33% 9% 19% 28% 10% 2	3150
July	1st to 10th	Day	26% 7% 18% 32% 15% 2	8746
	11th to 20th	Day	29% 6% 19% 27% 15% 4	8739
	21st to end	Day	23% 5% 14% 28% 22% 8%	9192
August	1st to 10th	Day	30% 6% 15% 33% 10% 4	6424
	11th to 20th	Day	35% 6% 24% 27% 6% 1	5966
	21st to end	Day	24% 5% 16% 38% 16% 1	6569
September	1st to 10th	Day	34% 6% 14% 28% 14% 5%	2607
	11th to 20th	Day	37% 6% 13% 29% 13% 2	2310
	21st to end	Day	34% 6% 14% 29% 14% 3	2310
October	1st to 10th	Day	36% 6% 17% 32% 8% 1	3526
	11th to 20th	Day	33% 6% 17% 27% 14% 3	3138
	21st to end	Day	38% 5% 10% 32% 13% 1	3272
November	1st to 10th	Day	50% 7% 11% 20% 9% 2	1703
	11th to 20th	Day	44% 6% 14% 24% 10% 1	1637
	21st to end	Day	45% 7% 16% 22% 8% 2	1470
December	1st to 10th	Day	50% 6% 13% 23% 7% 2	2360
	11th to 20th	Day	48% 7% 18% 21% 6% 1	2714
	21st to end	Day	37% 6% 12% 25% 17% 3	3575
January	1st to 10th	Night	53% 5% 12% 19% 9% 2	8769
	11th to 20th	Night	42% 5% 16% 20% 13% 4	8820
	21st to end	Night	41% 5% 17% 26% 11% 1	8994
February	1st to 10th	Night	50% 6% 13% 17% 12% 2	2919
	11th to 20th	Night	48% 7% 12% 19% 12% 1	2663
	21st to end	Night	47% 5% 13% 22% 12% 2	2139
March	1st to 10th	Night	43% 6% 18% 20% 11% 1	5496
	11th to 20th	Night	42% 6% 15% 23% 12% 1	5118
	21st to end	Night	61% 7% 12% 12% 8% 1	5577
April	1st to 10th	Night	49% 6% 14% 19% 12%	2026
	11th to 20th	Night	50% 7% 11% 21% 10% 1	1871
	21st to end	Night	47% 7% 14% 21% 10% 2	1890
May	1st to 10th	Night	47% 6% 9% 24% 14% 1	4963
	11th to 20th	Night	46% 7% 14% 24% 8% 1	4105
	21st to end	Night	42% 8% 17% 25% 8% 1	4526
June	1st to 10th	Night	49% 8% 12% 19% 11% 1	1470
	11th to 20th	Night	47% 9% 16% 19% 8% 2	1470
	21st to end	Night	33% 9% 20% 27% 10% 1	1470
July	1st to 10th	Night	27% 7% 18% 29% 18% 1	4105
	11th to 20th	Night	27% 7% 19% 31% 12% 4	4098
	21st to end	Night	25% 6% 13% 29% 19% 8%	4569
August	1st to 10th	Night	33% 7% 12% 29% 14% 4	3701
	11th to 20th	Night	38% 9% 23% 23% 6% 1	4165
	21st to end	Night	24% 6% 18% 36% 14% 2	4578
September	1st to 10th	Night	33% 6% 15% 26% 15% 5%	2010
	11th to 20th	Night	35% 7% 13% 27% 14% 4	2310
	21st to end	Night	32% 5% 18% 27% 15% 4	2310
October	1st to 10th	Night	31% 6% 15% 29% 17% 2	3875
	11th to 20th	Night	33% 6% 17% 25% 17% 2	4214
	21st to end	Night	36% 5% 12% 32% 14% 1	4704
November	1st to 10th	Night	47% 8% 11% 21% 11% 2	2794
	11th to 20th	Night	43% 7% 16% 20% 13% 1	2982
	21st to end	Night	42% 8% 17% 21% 10% 3	3150
December	1st to 10th	Night	50% 7% 16% 19% 7% 2	5040
	11th to 20th	Night	51% 7% 19% 18% 5%	5697
	21st to end	Night	40% 4 10% 26% 16% 3	7623

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% 34% 30% 13% 10%	220
	11th to 20th	Day	7% 9% 34% 32% 14% 5%	220
	21st to end	Day	8% 9% 29% 35% 16% 3	242
February	1st to 10th	Day	11% 8% 28% 37% 13% 3	231
	11th to 20th	Day	8% 6% 32% 36% 15% 3	330
	21st to end	Day	8% 10% 31% 33% 15% 3	380
March	1st to 10th	Day	9% 10% 35% 28% 13% 5%	540
	11th to 20th	Day	7% 12% 32% 32% 12% 4	540
	21st to end	Day	13% 14% 33% 22% 14% 5%	594
April	1st to 10th	Day	13% 11% 30% 30% 12% 4	540
	11th to 20th	Day	14% 11% 27% 29% 16% 4	532
	21st to end	Day	17% 11% 26% 27% 15% 4	540
May	1st to 10th	Day	17% 9% 24% 24% 20% 6%	604
	11th to 20th	Day	14% 7% 21% 31% 21% 6%	775
	21st to end	Day	17% 5% 21% 27% 23% 7%	844
June	1st to 10th	Day	16% 8% 24% 31% 18% 4	780
	11th to 20th	Day	17% 7% 26% 30% 16% 3	780
	21st to end	Day	9% 5% 23% 32% 24% 7%	780
July	1st to 10th	Day	9% 4 17% 34% 28% 8%	771
	11th to 20th	Day	11% 4 21% 33% 23% 8%	768
	21st to end	Day	6% 5% 21% 32% 26% 9%	791
August	1st to 10th	Day	8% 5% 21% 34% 24% 8%	567
	11th to 20th	Day	8% 2 21% 31% 29% 8%	557
	21st to end	Day	10% 6% 19% 31% 22% 12%	627
September	1st to 10th	Day	13% 6% 24% 29% 21% 7%	570
	11th to 20th	Day	16% 6% 20% 29% 21% 8%	570
	21st to end	Day	11% 11% 27% 31% 15% 4	570
October	1st to 10th	Day	16% 8% 19% 32% 19% 6%	464
	11th to 20th	Day	10% 8% 33% 26% 18% 6%	360
	21st to end	Day	14% 13% 32% 27% 10% 3	387
November	1st to 10th	Day	18% 8% 31% 27% 13% 3	330
	11th to 20th	Day	13% 9% 38% 25% 12% 2	307
	21st to end	Day	10% 7% 32% 29% 13% 9%	220
December	1st to 10th	Day	6% 9% 38% 29% 15% 4	220
	11th to 20th	Day	9% 11% 39% 28% 11% 2	220
	21st to end	Day	8% 5% 27% 33% 23% 4	242
January	1st to 10th	Night	8% 8% 35% 35% 12% 2	1050
	11th to 20th	Night	10% 7% 38% 32% 12% 1	1050
	21st to end	Night	11% 9% 34% 33% 12% 1	924
February	1st to 10th	Night	8% 8% 30% 36% 15% 2	840
	11th to 20th	Night	11% 6% 31% 38% 13% 1	824
	21st to end	Night	7% 5% 31% 35% 19% 4	692
March	1st to 10th	Night	8% 5% 33% 35% 15% 3	840
	11th to 20th	Night	9% 7% 36% 34% 13% 1	840
	21st to end	Night	14% 7% 29% 34% 13% 3	924
April	1st to 10th	Night	14% 7% 30% 35% 13% 2	766
	11th to 20th	Night	15% 8% 30% 35% 12%	623
	21st to end	Night	15% 8% 30% 35% 12%	630
May	1st to 10th	Night	18% 5% 26% 34% 16% 1	567
	11th to 20th	Night	13% 5% 24% 36% 21% 1	414
	21st to end	Night	18% 5% 20% 38% 18% 2	455
June	1st to 10th	Night	17% 8% 24% 37% 12% 2	420
	11th to 20th	Night	17% 4 31% 32% 15% 1	420
	21st to end	Night	11% 4 21% 41% 21% 1	420
July	1st to 10th	Night	9% 5% 15% 45% 26% 1	410
	11th to 20th	Night	9% 3 21% 45% 20% 2	408
	21st to end	Night	7% 2 22% 43% 26% 1	460
August	1st to 10th	Night	10% 4 15% 40% 28% 2	418
	11th to 20th	Night	9% 3 17% 44% 24% 1	621
	21st to end	Night	10% 5% 20% 41% 23% 1	693
September	1st to 10th	Night	13% 4 21% 40% 20% 2	713
	11th to 20th	Night	16% 4 17% 38% 24% 2	840
	21st to end	Night	11% 5% 30% 36% 16% 2	840
October	1st to 10th	Night	15% 5% 24% 37% 17% 2	840
	11th to 20th	Night	11% 7% 33% 33% 14% 3	840
	21st to end	Night	11% 8% 34% 34% 12% 1	912
November	1st to 10th	Night	14% 7% 38% 31% 8% 1	949
	11th to 20th	Night	10% 10% 40% 29% 9% 2	1050
	21st to end	Night	10% 5% 37% 35% 10% 2	1050
December	1st to 10th	Night	10% 8% 33% 33% 14% 2	1050
	11th to 20th	Night	8% 8% 37% 35% 11% 1	1050
	21st to end	Night	12% 5% 34% 33% 13% 3	1155

Page generated at 2026-10-26 02:37:51. Version ac07

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