Apgar Village
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Apgar Village clear sky chart from 2005-11-06 to 2024-03-01.

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	14% 14% 5% 7% 5% 3 4 4 5% 6% 32%	78008
	Night	15% 18% 5% 7% 5% 3 4 4 4 6% 29%	81348
Transparency	Day	53% 9% 13% 15% 8% 1	77725
	Night	57% 9% 12% 14% 7% 1	81211
Seeing	Day	22% 19% 29% 21% 9% 1	14235
	Night	26% 11% 28% 26% 8% 1	23667

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	13% 36% 13% 13% 6% 3 3 2 2 3 6%	2219
	11th to 20th	Day	18% 22% 6% 11% 5% 2 5% 3 3 3 21%	2460
	21st to end	Day	20% 32% 7% 13% 4 2 2 2 2 4 12%	2794
February	1st to 10th	Day	20% 23% 8% 10% 8% 3 3 3 3 4 16%	1582
	11th to 20th	Day	13% 26% 7% 10% 6% 3 4 4 4 5% 16%	1674
	21st to end	Day	10% 26% 9% 14% 8% 3 4 3 3 3 17%	1570
March	1st to 10th	Day	13% 25% 7% 10% 6% 3 4 4 4 5% 19%	1801
	11th to 20th	Day	17% 21% 5% 6% 5% 3 4 4 5% 7% 23%	1965
	21st to end	Day	14% 22% 6% 8% 6% 4 5% 4 5% 5% 19%	2189
April	1st to 10th	Day	12% 17% 7% 10% 7% 4 5% 6% 6% 6% 20%	2179
	11th to 20th	Day	17% 17% 5% 8% 7% 3 6% 5% 5% 5% 23%	2310
	21st to end	Day	14% 15% 6% 9% 6% 4 4 5% 6% 6% 26%	2340
May	1st to 10th	Day	14% 11% 4 7% 6% 4 6% 4 6% 7% 30%	2340
	11th to 20th	Day	12% 9% 3 7% 7% 4 6% 6% 6% 8% 33%	2564
	21st to end	Day	22% 10% 3 7% 6% 4 6% 5% 6% 7% 24%	2917
June	1st to 10th	Day	22% 8% 4 7% 6% 4 5% 5% 7% 6% 27%	2700
	11th to 20th	Day	23% 7% 4 7% 7% 4 6% 6% 6% 7% 25%	2700
	21st to end	Day	10% 5% 2 5% 5% 3 5% 5% 7% 8% 45%	2700
July	1st to 10th	Day	5% 3 2 3 4 3 4 5% 6% 7% 59%	2700
	11th to 20th	Day	5% 3 1 3 3 2 4 4 6% 7% 62%	2693
	21st to end	Day	3 2 1 2 3 2 3 3 4 7% 70%	2741
August	1st to 10th	Day	5% 3 2 3 3 2 3 4 5% 8% 61%	2461
	11th to 20th	Day	7% 3 1 3 3 2 4 5% 6% 7% 59%	2299
	21st to end	Day	8% 4 2 3 5% 4 4 5% 6% 6% 52%	2574
September	1st to 10th	Day	9% 5% 2 5% 5% 2 4 5% 5% 7% 52%	2175
	11th to 20th	Day	11% 6% 3 5% 6% 3 4 5% 5% 6% 46%	1980
	21st to end	Day	15% 7% 3 6% 5% 3 3 4 5% 7% 43%	1980
October	1st to 10th	Day	15% 10% 3 6% 5% 3 5% 4 4 6% 39%	1922
	11th to 20th	Day	17% 12% 4 6% 6% 3 4 5% 6% 7% 31%	1704
	21st to end	Day	20% 16% 5% 8% 5% 2 2 4 4 6% 27%	1782
November	1st to 10th	Day	24% 21% 6% 9% 5% 2 3 3 5% 5% 17%	1646
	11th to 20th	Day	20% 23% 6% 10% 4 3 3 3 3 5% 20%	1520
	21st to end	Day	16% 24% 8% 10% 7% 3 4 4 4 6% 15%	1373
December	1st to 10th	Day	18% 25% 9% 9% 5% 3 4 4 4 4 17%	1330
	11th to 20th	Day	21% 27% 7% 9% 5% 2 4 4 4 6% 11%	1682
	21st to end	Day	16% 23% 9% 12% 6% 3 4 4 4 5% 13%	2442
January	1st to 10th	Night	15% 40% 10% 10% 5% 2 3 2 2 3 7%	4726
	11th to 20th	Night	15% 19% 7% 10% 7% 3 4 4 4 5% 22%	4468
	21st to end	Night	21% 32% 7% 8% 4 2 3 3 3 4 12%	4862
February	1st to 10th	Night	19% 24% 7% 9% 5% 3 4 3 4 5% 18%	2596
	11th to 20th	Night	15% 26% 7% 10% 7% 3 3 3 3 4 20%	2389
	21st to end	Night	10% 26% 8% 12% 7% 3 4 4 4 5% 18%	1884
March	1st to 10th	Night	16% 22% 6% 10% 5% 2 4 3 4 6% 21%	2165
	11th to 20th	Night	18% 17% 5% 7% 5% 3 5% 5% 6% 6% 25%	1994
	21st to end	Night	14% 23% 6% 7% 6% 3 4 4 4 6% 22%	2165
April	1st to 10th	Night	12% 18% 4 6% 7% 3 5% 4 5% 6% 29%	1780
	11th to 20th	Night	15% 15% 6% 7% 7% 3 4 5% 3 6% 29%	1601
	21st to end	Night	14% 14% 3 6% 6% 3 5% 4 6% 6% 33%	1620
May	1st to 10th	Night	13% 10% 2 6% 7% 4 6% 5% 7% 8% 32%	1620
	11th to 20th	Night	13% 8% 2 6% 5% 4 6% 4 7% 8% 36%	1323
	21st to end	Night	19% 8% 3 7% 5% 3 5% 5% 6% 7% 32%	1358
June	1st to 10th	Night	21% 7% 3 5% 5% 3 5% 5% 5% 8% 35%	1260
	11th to 20th	Night	23% 6% 3 5% 5% 4 5% 7% 6% 6% 30%	1260
	21st to end	Night	8% 4 1 4 4 2 5% 4 5% 8% 54%	1260
July	1st to 10th	Night	3 2 1 4 3 2 3 3 5% 7% 67%	1260
	11th to 20th	Night	5% 3 1 2 3 1 2 2 4 6% 69%	1264
	21st to end	Night	2 2 2 2 1 2 3 4 7% 75%	1576
August	1st to 10th	Night	4 3 1 3 2 2 3 3 4 9% 67%	1476
	11th to 20th	Night	5% 2 2 2 3 2 2 4 5% 9% 64%	1602
	21st to end	Night	8% 2 1 3 4 2 4 4 6% 7% 60%	1782
September	1st to 10th	Night	7% 5% 2 3 4 3 4 6% 4 6% 57%	1782
	11th to 20th	Night	9% 5% 2 4 4 2 4 5% 5% 8% 51%	1980
	21st to end	Night	14% 6% 2 4 3 2 4 4 5% 8% 48%	1980
October	1st to 10th	Night	14% 9% 3 6% 4 3 5% 4 5% 6% 43%	2037
	11th to 20th	Night	17% 9% 2 4 5% 3 5% 5% 6% 7% 38%	2254
	21st to end	Night	19% 16% 4 7% 5% 3 3 3 4 6% 30%	2574
November	1st to 10th	Night	24% 20% 4 5% 6% 3 3 4 4 6% 20%	2413
	11th to 20th	Night	20% 24% 5% 7% 4 3 3 3 4 4 22%	2660
	21st to end	Night	19% 22% 6% 10% 7% 2 3 3 3 5% 20%	2803
December	1st to 10th	Night	17% 27% 7% 9% 6% 3 4 3 3 4 18%	2850
	11th to 20th	Night	18% 28% 7% 11% 5% 3 3 3 3 5% 13%	3510
	21st to end	Night	15% 23% 8% 11% 8% 4 5% 4 4 5% 12%	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	84% 8% 4 2 1	2219
	11th to 20th	Day	69% 6% 11% 5% 7% 1	2484
	21st to end	Day	77% 9% 6% 6% 1	2794
February	1st to 10th	Day	75% 8% 7% 6% 3 1	1582
	11th to 20th	Day	72% 9% 10% 5% 3	1683
	21st to end	Day	75% 7% 7% 6% 4 1	1570
March	1st to 10th	Day	68% 10% 11% 8% 2	1801
	11th to 20th	Day	63% 9% 13% 11% 4	1966
	21st to end	Day	68% 11% 12% 8% 2	2189
April	1st to 10th	Day	64% 10% 13% 11% 1	2179
	11th to 20th	Day	64% 11% 12% 12% 3	2310
	21st to end	Day	59% 11% 13% 14% 2 1	2340
May	1st to 10th	Day	54% 11% 15% 16% 5%	2340
	11th to 20th	Day	49% 12% 18% 17% 5%	2568
	21st to end	Day	59% 12% 16% 10% 3	2918
June	1st to 10th	Day	57% 10% 14% 15% 4	2700
	11th to 20th	Day	59% 9% 13% 14% 5% 1	2700
	21st to end	Day	35% 11% 17% 24% 11% 1	2700
July	1st to 10th	Day	25% 8% 13% 30% 19% 5%	2626
	11th to 20th	Day	21% 8% 13% 26% 28% 5%	2612
	21st to end	Day	15% 6% 10% 27% 36% 7%	2589
August	1st to 10th	Day	21% 8% 14% 28% 22% 6%	2444
	11th to 20th	Day	24% 8% 15% 31% 20% 2	2299
	21st to end	Day	31% 9% 11% 25% 19% 4	2574
September	1st to 10th	Day	33% 8% 13% 25% 17% 5%	2175
	11th to 20th	Day	38% 10% 12% 24% 14% 2	1980
	21st to end	Day	43% 10% 17% 20% 10% 1	1980
October	1st to 10th	Day	46% 10% 17% 19% 7%	1922
	11th to 20th	Day	52% 13% 17% 13% 5%	1704
	21st to end	Day	60% 9% 14% 13% 4	1782
November	1st to 10th	Day	72% 8% 10% 7% 3 1	1646
	11th to 20th	Day	68% 10% 12% 5% 4 1	1520
	21st to end	Day	69% 12% 9% 6% 3	1373
December	1st to 10th	Day	72% 8% 9% 9% 2	1330
	11th to 20th	Day	75% 10% 11% 4 1	1684
	21st to end	Day	68% 9% 13% 8% 2	2442
January	1st to 10th	Night	85% 6% 4 3 1	4726
	11th to 20th	Night	64% 7% 9% 7% 7% 5%	4506
	21st to end	Night	77% 7% 7% 6% 2	4862
February	1st to 10th	Night	72% 8% 7% 7% 5% 1	2596
	11th to 20th	Night	72% 8% 9% 8% 3	2390
	21st to end	Night	71% 8% 6% 11% 3 1	1884
March	1st to 10th	Night	67% 8% 12% 8% 5%	2165
	11th to 20th	Night	61% 10% 13% 14% 3	1994
	21st to end	Night	65% 11% 12% 10% 3	2165
April	1st to 10th	Night	56% 11% 16% 15% 3	1780
	11th to 20th	Night	59% 8% 12% 16% 5%	1601
	21st to end	Night	51% 11% 14% 17% 5% 1	1620
May	1st to 10th	Night	48% 13% 17% 17% 5%	1620
	11th to 20th	Night	44% 13% 16% 20% 7%	1323
	21st to end	Night	50% 13% 19% 13% 4	1358
June	1st to 10th	Night	48% 11% 18% 18% 6%	1260
	11th to 20th	Night	53% 12% 12% 17% 6% 1	1260
	21st to end	Night	29% 9% 21% 26% 14% 1	1260
July	1st to 10th	Night	19% 6% 14% 31% 24% 6%	1225
	11th to 20th	Night	18% 6% 14% 28% 27% 8%	1222
	21st to end	Night	12% 4 9% 29% 34% 10%	1488
August	1st to 10th	Night	17% 7% 14% 33% 22% 8%	1468
	11th to 20th	Night	17% 8% 14% 36% 20% 4	1602
	21st to end	Night	25% 7% 13% 27% 24% 3	1782
September	1st to 10th	Night	26% 10% 16% 25% 17% 6%	1782
	11th to 20th	Night	31% 10% 14% 28% 15% 2	1980
	21st to end	Night	36% 10% 18% 21% 12% 2	1980
October	1st to 10th	Night	44% 11% 15% 22% 8%	2037
	11th to 20th	Night	45% 11% 19% 18% 7%	2254
	21st to end	Night	58% 9% 14% 14% 5%	2574
November	1st to 10th	Night	66% 9% 11% 9% 4 1	2413
	11th to 20th	Night	67% 10% 11% 7% 4	2660
	21st to end	Night	68% 9% 11% 8% 3	2803
December	1st to 10th	Night	72% 7% 9% 9% 3	2850
	11th to 20th	Night	75% 8% 10% 6% 1	3507
	21st to end	Night	69% 11% 11% 7% 3	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	29% 16% 26% 16% 11% 2	180
	11th to 20th	Day	37% 17% 22% 13% 11%	180
	21st to end	Day	25% 22% 35% 12% 6%	198
February	1st to 10th	Day	30% 24% 35% 9% 1	210
	11th to 20th	Day	26% 25% 24% 19% 6%	279
	21st to end	Day	30% 23% 30% 13% 3	382
March	1st to 10th	Day	34% 23% 24% 13% 5%	421
	11th to 20th	Day	26% 20% 28% 16% 8% 2	420
	21st to end	Day	31% 22% 28% 12% 5% 2	462
April	1st to 10th	Day	26% 23% 32% 16% 3	420
	11th to 20th	Day	32% 24% 26% 13% 5%	412
	21st to end	Day	25% 21% 30% 16% 5% 2	420
May	1st to 10th	Day	19% 18% 27% 26% 8% 2	423
	11th to 20th	Day	23% 14% 24% 24% 13% 2	553
	21st to end	Day	27% 13% 19% 23% 15% 2	679
June	1st to 10th	Day	22% 15% 25% 25% 11% 2	630
	11th to 20th	Day	28% 20% 24% 19% 8%	630
	21st to end	Day	14% 14% 28% 28% 14% 2	630
July	1st to 10th	Day	9% 11% 28% 35% 15% 2	621
	11th to 20th	Day	9% 16% 32% 31% 11% 1	611
	21st to end	Day	4 20% 35% 31% 9% 1	487
August	1st to 10th	Day	9% 15% 38% 27% 10% 1	447
	11th to 20th	Day	9% 15% 35% 26% 12% 3	437
	21st to end	Day	11% 19% 36% 25% 8% 1	495
September	1st to 10th	Day	16% 22% 32% 22% 8% 2	450
	11th to 20th	Day	17% 24% 27% 22% 8% 2	450
	21st to end	Day	23% 23% 30% 16% 7% 1	450
October	1st to 10th	Day	21% 17% 33% 21% 8% 1	392
	11th to 20th	Day	27% 17% 25% 17% 10% 3	270
	21st to end	Day	34% 22% 21% 18% 4 1	297
November	1st to 10th	Day	36% 19% 27% 16% 2	270
	11th to 20th	Day	33% 16% 30% 15% 6%	270
	21st to end	Day	28% 19% 28% 13% 11%	201
December	1st to 10th	Day	38% 19% 21% 11% 10% 1	180
	11th to 20th	Day	33% 15% 34% 16% 2 1	180
	21st to end	Day	23% 21% 31% 19% 6% 1	198
January	1st to 10th	Night	37% 16% 27% 17% 4	950
	11th to 20th	Night	34% 12% 31% 18% 5% 1	807
	21st to end	Night	30% 12% 36% 19% 3	836
February	1st to 10th	Night	32% 12% 34% 18% 3	760
	11th to 20th	Night	30% 14% 35% 18% 3	744
	21st to end	Night	23% 18% 30% 24% 5%	628
March	1st to 10th	Night	29% 15% 32% 19% 4	722
	11th to 20th	Night	30% 12% 25% 26% 6% 1	720
	21st to end	Night	30% 12% 27% 23% 7%	792
April	1st to 10th	Night	23% 14% 29% 26% 8%	700
	11th to 20th	Night	28% 14% 30% 21% 7%	533
	21st to end	Night	24% 13% 25% 29% 9% 1	540
May	1st to 10th	Night	22% 9% 23% 34% 11% 1	540
	11th to 20th	Night	17% 7% 22% 37% 16% 2	369
	21st to end	Night	24% 10% 21% 23% 20% 1	389
June	1st to 10th	Night	24% 8% 22% 29% 15% 3	360
	11th to 20th	Night	28% 10% 24% 27% 11%	360
	21st to end	Night	11% 4 27% 38% 19% 1	360
July	1st to 10th	Night	7% 4 17% 54% 17% 1	350
	11th to 20th	Night	8% 5% 24% 51% 12%	348
	21st to end	Night	4 5% 21% 53% 16%	394
August	1st to 10th	Night	6% 6% 19% 48% 20%	402
	11th to 20th	Night	6% 6% 25% 41% 21% 1	534
	21st to end	Night	9% 8% 24% 42% 17% 1	594
September	1st to 10th	Night	9% 9% 28% 35% 16% 3	670
	11th to 20th	Night	12% 8% 23% 34% 20% 3	720
	21st to end	Night	20% 8% 22% 35% 14% 2	720
October	1st to 10th	Night	21% 8% 28% 33% 10% 1	720
	11th to 20th	Night	23% 8% 27% 31% 10% 1	720
	21st to end	Night	32% 12% 26% 24% 6%	792
November	1st to 10th	Night	38% 10% 29% 21% 2	748
	11th to 20th	Night	36% 16% 28% 18% 3	950
	21st to end	Night	32% 14% 27% 22% 5%	950
December	1st to 10th	Night	32% 13% 32% 18% 5%	950
	11th to 20th	Night	33% 13% 33% 19% 2	950
	21st to end	Night	34% 15% 30% 17% 4	1045

Page generated at 2024-02-27 04:30:19. Version ac07

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