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 2024-04-03.

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	9% 8% 4 7% 6% 4 5% 5% 6% 8% 38%	78269
	Night	7% 9% 4 8% 6% 4 5% 6% 6% 8% 37%	81803
Transparency	Day	42% 7% 15% 24% 11% 2	77974
	Night	43% 7% 14% 22% 11% 2	81678
Seeing	Day	13% 7% 25% 30% 19% 6%	14485
	Night	12% 6% 30% 35% 15% 2	23831

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	4 9% 7% 10% 7% 4 5% 6% 7% 8% 33%	2219
	11th to 20th	Day	4 8% 4 11% 9% 4 5% 8% 8% 6% 33%	2213
	21st to end	Day	4 8% 4 8% 8% 4 5% 5% 7% 8% 40%	2794
February	1st to 10th	Day	5% 10% 6% 10% 9% 5% 8% 6% 6% 8% 28%	1538
	11th to 20th	Day	6% 11% 6% 9% 7% 5% 6% 6% 7% 8% 28%	1665
	21st to end	Day	4 11% 9% 10% 7% 5% 6% 4 8% 8% 29%	1510
March	1st to 10th	Day	5% 11% 6% 11% 9% 3 6% 6% 6% 8% 31%	1900
	11th to 20th	Day	7% 9% 4 7% 7% 4 5% 6% 6% 9% 37%	2080
	21st to end	Day	9% 14% 6% 8% 6% 4 5% 5% 6% 8% 28%	2306
April	1st to 10th	Day	9% 11% 5% 10% 7% 4 5% 6% 6% 7% 30%	2247
	11th to 20th	Day	11% 11% 3 8% 7% 4 6% 5% 6% 8% 31%	2310
	21st to end	Day	12% 11% 3 8% 7% 3 5% 6% 5% 8% 32%	2340
May	1st to 10th	Day	14% 10% 4 7% 7% 4 6% 5% 5% 8% 31%	2444
	11th to 20th	Day	11% 6% 3 6% 7% 4 6% 5% 6% 10% 36%	2654
	21st to end	Day	20% 7% 3 6% 6% 4 5% 5% 5% 8% 32%	2917
June	1st to 10th	Day	16% 7% 2 6% 6% 4 5% 7% 7% 8% 32%	2700
	11th to 20th	Day	19% 7% 3 6% 6% 4 6% 6% 6% 7% 29%	2700
	21st to end	Day	8% 5% 2 5% 5% 3 5% 6% 8% 10% 43%	2700
July	1st to 10th	Day	8% 4 2 5% 5% 4 6% 6% 7% 9% 44%	2700
	11th to 20th	Day	9% 5% 2 5% 4 3 5% 5% 6% 9% 47%	2700
	21st to end	Day	5% 3 1 3 4 2 4 5% 7% 10% 56%	2889
August	1st to 10th	Day	8% 5% 2 5% 5% 3 4 5% 6% 9% 47%	2507
	11th to 20th	Day	8% 4 2 4 4 2 5% 5% 6% 9% 50%	2301
	21st to end	Day	10% 4 2 3 4 3 4 5% 5% 9% 51%	2574
September	1st to 10th	Day	9% 6% 2 5% 5% 3 4 4 5% 6% 51%	2236
	11th to 20th	Day	15% 7% 3 4 3 3 4 4 5% 7% 45%	1980
	21st to end	Day	9% 7% 2 5% 5% 4 4 4 5% 8% 46%	1980
October	1st to 10th	Day	13% 9% 3 6% 6% 3 4 5% 5% 7% 40%	1890
	11th to 20th	Day	9% 8% 2 8% 6% 4 5% 5% 6% 7% 40%	1689
	21st to end	Day	7% 10% 3 7% 6% 3 6% 6% 6% 8% 37%	1782
November	1st to 10th	Day	10% 14% 6% 8% 5% 4 5% 5% 5% 8% 30%	1538
	11th to 20th	Day	7% 10% 3 8% 6% 3 5% 4 6% 8% 39%	1482
	21st to end	Day	5% 9% 6% 8% 5% 5% 5% 5% 8% 10% 34%	1330
December	1st to 10th	Day	5% 12% 6% 10% 7% 4 7% 5% 5% 7% 33%	1330
	11th to 20th	Day	4 11% 5% 12% 8% 4 5% 6% 7% 7% 32%	1682
	21st to end	Day	4 8% 3 6% 6% 3 5% 5% 6% 10% 43%	2442
January	1st to 10th	Night	4 12% 5% 11% 9% 4 6% 6% 6% 9% 27%	4726
	11th to 20th	Night	3 7% 6% 12% 7% 5% 6% 7% 6% 8% 33%	4699
	21st to end	Night	4 10% 5% 9% 7% 3 5% 5% 6% 7% 40%	4862
February	1st to 10th	Night	5% 11% 5% 11% 7% 5% 6% 6% 5% 9% 31%	2641
	11th to 20th	Night	6% 13% 5% 10% 7% 4 6% 6% 7% 8% 29%	2402
	21st to end	Night	4 9% 6% 10% 9% 4 6% 5% 6% 8% 33%	1941
March	1st to 10th	Night	4 11% 4 10% 9% 5% 6% 5% 7% 9% 30%	2280
	11th to 20th	Night	6% 11% 5% 7% 6% 5% 5% 5% 6% 9% 35%	2098
	21st to end	Night	7% 13% 5% 10% 7% 4 6% 5% 7% 9% 28%	2290
April	1st to 10th	Night	8% 12% 4 10% 6% 4 5% 6% 6% 9% 30%	1758
	11th to 20th	Night	10% 13% 4 9% 6% 4 5% 4 6% 7% 32%	1601
	21st to end	Night	10% 11% 4 8% 7% 4 4 6% 5% 9% 32%	1620
May	1st to 10th	Night	11% 10% 4 7% 5% 4 5% 6% 6% 9% 33%	1512
	11th to 20th	Night	11% 7% 2 5% 5% 3 4 6% 6% 9% 41%	1239
	21st to end	Night	18% 6% 4 6% 5% 4 5% 5% 7% 8% 32%	1358
June	1st to 10th	Night	14% 7% 3 6% 7% 4 6% 7% 6% 8% 32%	1260
	11th to 20th	Night	16% 6% 3 7% 7% 4 6% 6% 7% 9% 31%	1260
	21st to end	Night	7% 4 2 5% 5% 3 6% 7% 6% 9% 46%	1260
July	1st to 10th	Night	8% 5% 2 4 5% 3 5% 5% 6% 10% 47%	1260
	11th to 20th	Night	7% 5% 2 4 4 3 4 6% 8% 10% 47%	1260
	21st to end	Night	4 4 1 4 4 2 5% 5% 7% 8% 57%	1426
August	1st to 10th	Night	8% 5% 2 6% 5% 4 5% 5% 6% 9% 46%	1432
	11th to 20th	Night	8% 3 2 4 4 2 4 5% 7% 10% 51%	1599
	21st to end	Night	9% 4 2 4 3 2 4 5% 6% 8% 52%	1782
September	1st to 10th	Night	10% 5% 3 5% 4 3 4 5% 6% 8% 47%	1722
	11th to 20th	Night	13% 7% 2 5% 4 2 3 4 5% 7% 49%	1980
	21st to end	Night	9% 6% 2 4 4 3 4 5% 7% 8% 47%	1980
October	1st to 10th	Night	11% 8% 3 5% 5% 4 4 6% 6% 8% 41%	2070
	11th to 20th	Night	9% 7% 3 6% 5% 3 5% 6% 6% 9% 42%	2268
	21st to end	Night	7% 10% 4 8% 5% 4 5% 5% 7% 8% 37%	2574
November	1st to 10th	Night	9% 14% 4 7% 6% 4 5% 5% 6% 8% 34%	2521
	11th to 20th	Night	5% 10% 4 7% 6% 4 6% 6% 7% 7% 38%	2698
	21st to end	Night	5% 10% 4 8% 5% 3 5% 5% 7% 9% 38%	2850
December	1st to 10th	Night	4 12% 5% 9% 6% 4 6% 6% 6% 7% 34%	2850
	11th to 20th	Night	3 8% 4 10% 8% 4 6% 6% 7% 9% 32%	3510
	21st to end	Night	4 8% 4 7% 6% 4 5% 5% 6% 7% 44%	5214

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	45% 7% 15% 23% 9% 2	2219
	11th to 20th	Day	47% 7% 11% 15% 16% 4	2234
	21st to end	Day	40% 8% 13% 30% 8% 1	2794
February	1st to 10th	Day	54% 7% 14% 15% 8% 2	1538
	11th to 20th	Day	50% 8% 13% 19% 9% 1	1674
	21st to end	Day	51% 6% 12% 20% 11% 1	1510
March	1st to 10th	Day	50% 7% 16% 17% 9% 1	1900
	11th to 20th	Day	43% 7% 13% 23% 12% 1	2081
	21st to end	Day	53% 8% 16% 17% 7%	2306
April	1st to 10th	Day	50% 8% 15% 18% 8% 1	2247
	11th to 20th	Day	50% 5% 12% 22% 10% 2	2310
	21st to end	Day	50% 6% 13% 20% 10% 1	2340
May	1st to 10th	Day	50% 9% 12% 21% 8% 1	2444
	11th to 20th	Day	42% 8% 15% 24% 10% 1	2658
	21st to end	Day	50% 6% 12% 23% 7% 1	2918
June	1st to 10th	Day	47% 8% 15% 21% 8% 1	2700
	11th to 20th	Day	50% 8% 14% 18% 7% 2	2700
	21st to end	Day	33% 9% 19% 28% 9% 2	2700
July	1st to 10th	Day	33% 9% 18% 26% 11% 2	2626
	11th to 20th	Day	33% 9% 18% 26% 13% 1	2619
	21st to end	Day	22% 8% 18% 33% 16% 2	2728
August	1st to 10th	Day	32% 7% 17% 31% 10% 2	2490
	11th to 20th	Day	29% 8% 21% 30% 11% 3	2301
	21st to end	Day	30% 7% 17% 28% 16% 2	2574
September	1st to 10th	Day	33% 6% 14% 27% 14% 5%	2236
	11th to 20th	Day	38% 6% 13% 27% 13% 3	1980
	21st to end	Day	36% 6% 14% 28% 12% 3	1980
October	1st to 10th	Day	44% 7% 13% 26% 9% 2	1890
	11th to 20th	Day	41% 6% 14% 26% 10% 3	1689
	21st to end	Day	44% 6% 12% 25% 11% 1	1782
November	1st to 10th	Day	51% 8% 11% 20% 9% 2	1538
	11th to 20th	Day	44% 6% 15% 24% 10% 1	1482
	21st to end	Day	42% 7% 17% 23% 9% 2	1330
December	1st to 10th	Day	50% 7% 11% 17% 12% 3	1330
	11th to 20th	Day	49% 7% 14% 22% 7% 1	1684
	21st to end	Day	35% 7% 12% 24% 18% 5%	2442
January	1st to 10th	Night	51% 7% 14% 21% 6% 2	4726
	11th to 20th	Night	48% 6% 11% 15% 15% 4	4740
	21st to end	Night	42% 6% 14% 25% 11% 1	4862
February	1st to 10th	Night	50% 6% 13% 18% 11% 2	2641
	11th to 20th	Night	49% 7% 12% 19% 11% 1	2403
	21st to end	Night	47% 5% 12% 21% 11% 2	1941
March	1st to 10th	Night	49% 7% 13% 23% 7% 1	2280
	11th to 20th	Night	45% 5% 15% 20% 13% 1	2098
	21st to end	Night	53% 7% 15% 16% 7% 1	2290
April	1st to 10th	Night	49% 6% 15% 18% 12%	1758
	11th to 20th	Night	51% 7% 11% 21% 9% 1	1601
	21st to end	Night	47% 7% 15% 20% 9% 2	1620
May	1st to 10th	Night	46% 8% 13% 21% 11% 1	1512
	11th to 20th	Night	38% 7% 15% 26% 12% 1	1239
	21st to end	Night	49% 7% 15% 20% 8% 2	1358
June	1st to 10th	Night	48% 9% 14% 19% 10%	1260
	11th to 20th	Night	47% 9% 16% 18% 8% 2	1260
	21st to end	Night	32% 10% 20% 26% 11% 1	1260
July	1st to 10th	Night	32% 9% 19% 27% 12% 1	1225
	11th to 20th	Night	30% 12% 18% 25% 12% 3	1218
	21st to end	Night	23% 9% 17% 32% 18% 2	1347
August	1st to 10th	Night	33% 9% 15% 28% 13% 2	1424
	11th to 20th	Night	26% 9% 19% 31% 13% 2	1599
	21st to end	Night	28% 8% 14% 29% 17% 4	1782
September	1st to 10th	Night	34% 7% 15% 25% 15% 5%	1722
	11th to 20th	Night	36% 7% 12% 26% 14% 5%	1980
	21st to end	Night	33% 5% 18% 25% 14% 4	1980
October	1st to 10th	Night	40% 7% 13% 24% 14% 2	2070
	11th to 20th	Night	38% 8% 16% 24% 13% 3	2268
	21st to end	Night	42% 7% 14% 24% 11% 1	2574
November	1st to 10th	Night	48% 8% 11% 21% 11% 2	2521
	11th to 20th	Night	42% 8% 15% 20% 13% 2	2698
	21st to end	Night	41% 9% 17% 21% 10% 3	2850
December	1st to 10th	Night	48% 7% 13% 20% 10% 3	2850
	11th to 20th	Night	45% 9% 17% 22% 6% 1	3507
	21st to end	Night	38% 5% 11% 26% 15% 4	5214

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% 4 32% 31% 14% 11%	180
	11th to 20th	Day	6% 7% 29% 36% 16% 6%	180
	21st to end	Day	8% 8% 27% 37% 17% 4	198
February	1st to 10th	Day	12% 8% 28% 37% 11% 4	189
	11th to 20th	Day	9% 8% 32% 33% 15% 3	270
	21st to end	Day	8% 8% 30% 35% 16% 3	322
March	1st to 10th	Day	10% 10% 34% 29% 13% 5%	460
	11th to 20th	Day	8% 11% 30% 33% 14% 4	460
	21st to end	Day	13% 13% 32% 22% 15% 6%	506
April	1st to 10th	Day	12% 11% 30% 32% 12% 3	429
	11th to 20th	Day	14% 10% 27% 29% 17% 4	412
	21st to end	Day	19% 10% 26% 27% 15% 4	420
May	1st to 10th	Day	18% 10% 23% 21% 22% 7%	475
	11th to 20th	Day	15% 5% 21% 30% 23% 5%	625
	21st to end	Day	19% 4 20% 27% 22% 8%	679
June	1st to 10th	Day	17% 7% 22% 32% 19% 4	630
	11th to 20th	Day	20% 6% 25% 30% 16% 3	630
	21st to end	Day	9% 4 23% 32% 23% 8%	630
July	1st to 10th	Day	10% 4 18% 33% 27% 8%	621
	11th to 20th	Day	12% 5% 19% 33% 24% 7%	618
	21st to end	Day	5% 5% 20% 33% 27% 10%	635
August	1st to 10th	Day	9% 5% 22% 33% 22% 9%	447
	11th to 20th	Day	8% 2 21% 32% 28% 9%	437
	21st to end	Day	10% 6% 20% 32% 20% 13%	495
September	1st to 10th	Day	13% 6% 26% 31% 19% 4	450
	11th to 20th	Day	18% 7% 20% 28% 20% 6%	450
	21st to end	Day	14% 12% 25% 30% 15% 5%	450
October	1st to 10th	Day	18% 8% 18% 28% 21% 7%	360
	11th to 20th	Day	10% 8% 33% 26% 17% 7%	270
	21st to end	Day	14% 12% 33% 25% 13% 2	297
November	1st to 10th	Day	19% 8% 31% 26% 13% 3	270
	11th to 20th	Day	14% 9% 38% 27% 11% 2	252
	21st to end	Day	7% 8% 35% 27% 13% 10%	180
December	1st to 10th	Day	7% 8% 36% 30% 14% 4	180
	11th to 20th	Day	9% 9% 38% 29% 12% 2	180
	21st to end	Day	9% 4 26% 32% 25% 5%	198
January	1st to 10th	Night	8% 8% 34% 35% 12% 2	950
	11th to 20th	Night	9% 6% 36% 34% 13% 2	950
	21st to end	Night	11% 9% 32% 33% 13% 2	836
February	1st to 10th	Night	9% 9% 29% 35% 16% 2	760
	11th to 20th	Night	11% 6% 31% 37% 13% 1	744
	21st to end	Night	6% 6% 29% 35% 20% 4	628
March	1st to 10th	Night	9% 5% 32% 35% 16% 3	760
	11th to 20th	Night	10% 7% 35% 34% 13% 1	760
	21st to end	Night	14% 7% 28% 35% 14% 3	836
April	1st to 10th	Night	13% 6% 31% 35% 14% 2	666
	11th to 20th	Night	16% 6% 31% 34% 13%	533
	21st to end	Night	15% 8% 30% 34% 12% 1	540
May	1st to 10th	Night	17% 5% 26% 33% 17% 1	486
	11th to 20th	Night	13% 3 24% 36% 22% 1	354
	21st to end	Night	20% 4 20% 38% 16% 2	389
June	1st to 10th	Night	17% 5% 23% 38% 14% 2	360
	11th to 20th	Night	17% 3 29% 34% 15% 1	360
	21st to end	Night	10% 4 21% 41% 23% 2	360
July	1st to 10th	Night	9% 5% 14% 45% 27% 1	350
	11th to 20th	Night	9% 3 21% 44% 20% 2	348
	21st to end	Night	6% 1 22% 44% 26% 2	394
August	1st to 10th	Night	10% 3 15% 41% 28% 2	358
	11th to 20th	Night	9% 3 18% 45% 23% 2	531
	21st to end	Night	10% 5% 20% 40% 25% 1	594
September	1st to 10th	Night	13% 4 22% 39% 19% 2	611
	11th to 20th	Night	17% 4 18% 38% 22% 2	720
	21st to end	Night	12% 5% 30% 34% 17% 2	720
October	1st to 10th	Night	17% 4 22% 37% 18% 2	720
	11th to 20th	Night	12% 5% 33% 32% 15% 3	720
	21st to end	Night	12% 7% 34% 34% 12% 1	792
November	1st to 10th	Night	15% 7% 38% 30% 9% 2	856
	11th to 20th	Night	10% 10% 41% 29% 8% 2	950
	21st to end	Night	10% 6% 38% 34% 11% 3	950
December	1st to 10th	Night	10% 7% 31% 34% 15% 2	950
	11th to 20th	Night	8% 7% 37% 35% 11% 1	950
	21st to end	Night	13% 5% 33% 33% 14% 3	1045

Page generated at 2024-03-31 04:08:52. Version ac07

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