Nakusp
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nakusp clear sky chart from 2005-11-06 to 2024-03-28.

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	12% 12% 5% 9% 8% 4 6% 6% 6% 7% 27%	78544
	Night	13% 16% 6% 10% 8% 4 5% 5% 5% 6% 22%	81389
Transparency	Day	57% 9% 13% 14% 6% 1	78262
	Night	61% 9% 11% 13% 6% 1	81251
Seeing	Day	19% 17% 30% 24% 9% 1	14336
	Night	22% 11% 30% 28% 9%	23339

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% 23% 9% 15% 12% 6% 6% 5% 3 3 4	2356
	11th to 20th	Day	12% 18% 6% 10% 7% 5% 6% 9% 7% 8% 11%	2516
	21st to end	Day	11% 20% 8% 15% 13% 5% 6% 5% 5% 5% 8%	2794
February	1st to 10th	Day	13% 21% 6% 12% 10% 6% 5% 4 6% 5% 14%	1520
	11th to 20th	Day	9% 18% 8% 13% 10% 3 5% 5% 5% 5% 20%	1659
	21st to end	Day	7% 18% 8% 12% 10% 4 6% 6% 6% 6% 17%	1570
March	1st to 10th	Day	9% 16% 7% 11% 9% 6% 7% 6% 6% 6% 15%	1900
	11th to 20th	Day	12% 13% 6% 9% 8% 5% 6% 6% 6% 7% 23%	1933
	21st to end	Day	10% 18% 7% 11% 8% 5% 6% 5% 5% 6% 18%	2461
April	1st to 10th	Day	10% 15% 6% 12% 8% 5% 7% 5% 6% 8% 19%	2160
	11th to 20th	Day	12% 12% 6% 9% 8% 5% 7% 6% 6% 7% 22%	2218
	21st to end	Day	12% 13% 5% 10% 9% 4 6% 6% 5% 6% 24%	2393
May	1st to 10th	Day	11% 11% 4 8% 8% 4 6% 5% 6% 7% 32%	2520
	11th to 20th	Day	12% 8% 3 8% 7% 4 7% 5% 6% 9% 31%	2477
	21st to end	Day	14% 10% 4 9% 7% 4 6% 5% 6% 7% 27%	2899
June	1st to 10th	Day	20% 9% 4 8% 7% 4 6% 5% 5% 7% 26%	2700
	11th to 20th	Day	20% 10% 4 8% 8% 4 7% 6% 6% 7% 20%	2715
	21st to end	Day	10% 5% 3 7% 8% 5% 6% 7% 6% 7% 36%	2880
July	1st to 10th	Day	8% 5% 3 5% 6% 4 6% 5% 8% 8% 44%	2727
	11th to 20th	Day	6% 4 2 5% 6% 4 5% 6% 6% 8% 49%	2561
	21st to end	Day	5% 3 1 4 4 2 4 5% 6% 9% 57%	2741
August	1st to 10th	Day	5% 3 1 4 5% 3 4 5% 7% 7% 54%	2507
	11th to 20th	Day	6% 4 1 4 4 3 4 6% 6% 9% 54%	2448
	21st to end	Day	8% 5% 3 5% 6% 4 5% 6% 7% 9% 43%	2464
September	1st to 10th	Day	9% 6% 2 6% 5% 3 6% 5% 4 8% 46%	2160
	11th to 20th	Day	11% 7% 3 6% 7% 4 4 5% 5% 8% 38%	2084
	21st to end	Day	14% 9% 3 8% 6% 4 5% 5% 6% 7% 32%	1980
October	1st to 10th	Day	13% 10% 4 8% 6% 4 6% 6% 6% 7% 29%	1864
	11th to 20th	Day	18% 11% 5% 8% 7% 4 5% 5% 6% 6% 26%	1679
	21st to end	Day	20% 13% 6% 10% 7% 3 5% 5% 5% 7% 20%	1782
November	1st to 10th	Day	21% 15% 7% 12% 10% 6% 5% 5% 4 5% 10%	1652
	11th to 20th	Day	16% 17% 6% 10% 9% 5% 6% 6% 5% 6% 14%	1440
	21st to end	Day	14% 19% 8% 13% 11% 5% 7% 4 4 5% 11%	1330
December	1st to 10th	Day	14% 17% 7% 11% 12% 6% 7% 6% 6% 5% 10%	1330
	11th to 20th	Day	13% 24% 9% 14% 8% 7% 6% 5% 4 4 5%	1682
	21st to end	Day	11% 17% 7% 13% 13% 8% 9% 6% 4 4 8%	2442
January	1st to 10th	Night	16% 33% 9% 13% 7% 4 5% 4 3 3 4	4616
	11th to 20th	Night	12% 17% 7% 14% 10% 5% 9% 6% 7% 8% 6%	4382
	21st to end	Night	16% 25% 9% 15% 10% 4 4 4 3 4 5%	4862
February	1st to 10th	Night	13% 26% 8% 14% 8% 4 6% 4 4 4 9%	2660
	11th to 20th	Night	12% 20% 8% 12% 9% 4 5% 4 4 5% 16%	2407
	21st to end	Night	8% 22% 8% 13% 10% 5% 5% 5% 5% 6% 12%	1884
March	1st to 10th	Night	11% 18% 7% 10% 9% 5% 6% 5% 6% 7% 15%	2280
	11th to 20th	Night	10% 18% 6% 9% 7% 3 5% 4 5% 7% 25%	2243
	21st to end	Night	11% 15% 5% 10% 8% 4 7% 6% 6% 6% 21%	2050
April	1st to 10th	Night	10% 13% 5% 9% 7% 3 6% 6% 7% 8% 27%	1800
	11th to 20th	Night	11% 14% 5% 8% 7% 4 6% 6% 6% 7% 26%	1692
	21st to end	Night	12% 11% 4 7% 6% 4 4 5% 6% 8% 33%	1566
May	1st to 10th	Night	10% 9% 3 7% 5% 4 6% 6% 7% 8% 36%	1440
	11th to 20th	Night	9% 7% 4 6% 5% 3 5% 5% 6% 10% 40%	1416
	21st to end	Night	14% 8% 4 6% 6% 3 5% 5% 6% 8% 34%	1375
June	1st to 10th	Night	19% 10% 3 6% 5% 3 5% 5% 6% 6% 32%	1260
	11th to 20th	Night	18% 8% 3 6% 6% 4 7% 6% 6% 9% 26%	1236
	21st to end	Night	6% 5% 2 6% 7% 4 5% 6% 5% 10% 43%	1080
July	1st to 10th	Night	6% 4 2 5% 5% 3 6% 5% 6% 8% 49%	1228
	11th to 20th	Night	6% 3 1 5% 5% 3 4 6% 7% 9% 52%	1395
	21st to end	Night	4 1 1 3 3 3 3 3 7% 8% 64%	1576
August	1st to 10th	Night	5% 3 2 3 4 2 3 5% 7% 7% 59%	1432
	11th to 20th	Night	4 3 2 3 4 2 3 3 6% 6% 63%	1450
	21st to end	Night	6% 4 2 4 4 2 4 5% 7% 8% 53%	1890
September	1st to 10th	Night	9% 5% 2 4 5% 3 4 5% 5% 7% 51%	1800
	11th to 20th	Night	10% 8% 3 6% 5% 3 4 4 5% 7% 46%	1876
	21st to end	Night	12% 9% 2 7% 5% 3 4 5% 5% 7% 41%	1980
October	1st to 10th	Night	13% 8% 3 7% 6% 3 5% 4 6% 7% 38%	2093
	11th to 20th	Night	16% 10% 3 8% 7% 4 5% 6% 6% 7% 29%	2280
	21st to end	Night	20% 13% 4 8% 7% 3 5% 6% 6% 6% 20%	2574
November	1st to 10th	Night	21% 18% 5% 11% 9% 4 7% 4 5% 5% 11%	2424
	11th to 20th	Night	17% 21% 6% 12% 9% 5% 6% 6% 4 5% 11%	2718
	21st to end	Night	15% 19% 9% 13% 11% 5% 6% 5% 4 4 10%	2850
December	1st to 10th	Night	14% 20% 7% 13% 10% 5% 6% 4 5% 5% 11%	2850
	11th to 20th	Night	15% 23% 9% 18% 12% 6% 5% 4 3 2 4	3510
	21st to end	Night	12% 20% 7% 13% 11% 6% 8% 6% 5% 5% 6%	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	81% 10% 5% 3 1	2356
	11th to 20th	Day	63% 10% 13% 8% 5% 1	2540
	21st to end	Day	79% 11% 5% 4 1	2794
February	1st to 10th	Day	72% 8% 9% 6% 4 1	1520
	11th to 20th	Day	67% 9% 11% 8% 4 1	1668
	21st to end	Day	69% 8% 11% 8% 3	1570
March	1st to 10th	Day	69% 10% 11% 6% 3	1900
	11th to 20th	Day	62% 8% 14% 13% 2	1933
	21st to end	Day	68% 10% 13% 6% 2	2461
April	1st to 10th	Day	66% 10% 13% 9% 2	2160
	11th to 20th	Day	62% 10% 13% 13% 3	2218
	21st to end	Day	63% 8% 14% 13% 2	2393
May	1st to 10th	Day	53% 9% 18% 16% 4	2520
	11th to 20th	Day	51% 10% 17% 19% 3	2480
	21st to end	Day	58% 8% 16% 16% 3	2900
June	1st to 10th	Day	62% 8% 11% 14% 5% 1	2700
	11th to 20th	Day	64% 10% 10% 12% 3	2715
	21st to end	Day	48% 10% 14% 20% 8% 1	2880
July	1st to 10th	Day	39% 9% 14% 21% 13% 4	2653
	11th to 20th	Day	34% 8% 17% 23% 16% 3	2483
	21st to end	Day	25% 7% 14% 28% 24% 2	2589
August	1st to 10th	Day	29% 9% 14% 26% 18% 4	2490
	11th to 20th	Day	28% 8% 16% 29% 16% 2	2448
	21st to end	Day	39% 9% 14% 26% 10% 1	2464
September	1st to 10th	Day	39% 7% 15% 27% 10% 2	2160
	11th to 20th	Day	43% 9% 13% 24% 10% 1	2084
	21st to end	Day	52% 9% 16% 15% 7% 1	1980
October	1st to 10th	Day	54% 9% 15% 20% 3	1864
	11th to 20th	Day	56% 9% 16% 16% 3	1679
	21st to end	Day	63% 8% 14% 13% 2	1782
November	1st to 10th	Day	75% 10% 8% 7% 1	1652
	11th to 20th	Day	70% 11% 10% 7% 3	1440
	21st to end	Day	71% 11% 11% 5% 2	1330
December	1st to 10th	Day	70% 10% 10% 9% 1	1330
	11th to 20th	Day	80% 10% 6% 3 2	1684
	21st to end	Day	70% 12% 8% 6% 3	2442
January	1st to 10th	Night	84% 7% 4 3 1	4616
	11th to 20th	Night	70% 8% 7% 9% 5% 1	4420
	21st to end	Night	84% 7% 4 3 1	4862
February	1st to 10th	Night	76% 7% 7% 6% 4	2660
	11th to 20th	Night	66% 10% 11% 9% 4 1	2409
	21st to end	Night	69% 8% 10% 9% 4	1884
March	1st to 10th	Night	65% 11% 11% 8% 5%	2280
	11th to 20th	Night	59% 7% 14% 15% 4	2244
	21st to end	Night	62% 11% 13% 10% 4	2050
April	1st to 10th	Night	54% 13% 17% 12% 4	1800
	11th to 20th	Night	56% 9% 16% 13% 5% 1	1692
	21st to end	Night	50% 10% 16% 18% 5%	1566
May	1st to 10th	Night	46% 9% 21% 16% 8%	1440
	11th to 20th	Night	42% 9% 22% 21% 6%	1416
	21st to end	Night	49% 9% 17% 21% 4	1375
June	1st to 10th	Night	53% 9% 12% 18% 7% 1	1260
	11th to 20th	Night	55% 11% 12% 17% 5%	1236
	21st to end	Night	38% 10% 16% 26% 9% 1	1080
July	1st to 10th	Night	34% 9% 14% 25% 15% 3	1193
	11th to 20th	Night	29% 8% 17% 26% 18% 3	1350
	21st to end	Night	18% 6% 16% 32% 26% 3	1488
August	1st to 10th	Night	23% 7% 15% 30% 20% 5%	1424
	11th to 20th	Night	21% 7% 16% 34% 20% 1	1450
	21st to end	Night	29% 9% 16% 31% 13% 1	1890
September	1st to 10th	Night	34% 7% 15% 28% 14% 3	1800
	11th to 20th	Night	39% 7% 13% 26% 12% 3	1876
	21st to end	Night	43% 9% 19% 18% 9% 1	1980
October	1st to 10th	Night	46% 9% 16% 23% 6%	2093
	11th to 20th	Night	54% 9% 16% 17% 5%	2280
	21st to end	Night	62% 8% 13% 14% 2	2574
November	1st to 10th	Night	72% 9% 9% 7% 3	2424
	11th to 20th	Night	72% 9% 9% 6% 3	2718
	21st to end	Night	74% 9% 9% 6% 1	2850
December	1st to 10th	Night	71% 9% 10% 8% 2	2850
	11th to 20th	Night	84% 8% 6% 3	3507
	21st to end	Night	75% 10% 8% 4 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	22% 22% 31% 15% 9% 1	180
	11th to 20th	Day	26% 24% 28% 16% 6% 1	180
	21st to end	Day	23% 20% 33% 16% 8% 1	198
February	1st to 10th	Day	28% 26% 31% 12% 3	180
	11th to 20th	Day	19% 22% 36% 15% 8%	337
	21st to end	Day	20% 20% 31% 21% 7% 1	382
March	1st to 10th	Day	20% 28% 30% 17% 5%	460
	11th to 20th	Day	20% 26% 24% 21% 8%	460
	21st to end	Day	23% 20% 28% 21% 7% 1	491
April	1st to 10th	Day	22% 21% 31% 21% 5% 1	420
	11th to 20th	Day	24% 20% 28% 18% 9% 1	412
	21st to end	Day	21% 20% 27% 24% 7% 2	420
May	1st to 10th	Day	18% 17% 28% 27% 9% 1	423
	11th to 20th	Day	18% 13% 28% 24% 16% 1	448
	21st to end	Day	19% 12% 25% 30% 14% 1	661
June	1st to 10th	Day	23% 16% 31% 23% 6%	630
	11th to 20th	Day	24% 15% 29% 24% 7% 1	645
	21st to end	Day	13% 11% 29% 34% 11% 1	810
July	1st to 10th	Day	15% 9% 27% 37% 10%	648
	11th to 20th	Day	11% 15% 33% 28% 12% 1	482
	21st to end	Day	8% 10% 34% 35% 11% 2	487
August	1st to 10th	Day	8% 12% 31% 33% 13% 3	447
	11th to 20th	Day	9% 13% 30% 33% 13% 3	437
	21st to end	Day	11% 17% 29% 29% 13% 1	495
September	1st to 10th	Day	16% 15% 32% 27% 10%	450
	11th to 20th	Day	17% 15% 30% 28% 9% 1	450
	21st to end	Day	20% 22% 29% 20% 9%	450
October	1st to 10th	Day	22% 16% 30% 21% 11%	450
	11th to 20th	Day	27% 14% 29% 18% 12%	329
	21st to end	Day	31% 20% 29% 16% 3 1	297
November	1st to 10th	Day	32% 17% 28% 19% 5%	259
	11th to 20th	Day	29% 16% 31% 16% 8%	180
	21st to end	Day	22% 16% 32% 22% 5% 3	180
December	1st to 10th	Day	26% 17% 24% 20% 13% 1	180
	11th to 20th	Day	28% 16% 36% 16% 4 1	180
	21st to end	Day	25% 13% 38% 19% 5%	198
January	1st to 10th	Night	34% 17% 28% 18% 4	879
	11th to 20th	Night	29% 12% 34% 21% 4	760
	21st to end	Night	24% 15% 33% 25% 4	836
February	1st to 10th	Night	27% 14% 33% 19% 6%	760
	11th to 20th	Night	23% 13% 34% 25% 5%	744
	21st to end	Night	19% 12% 33% 25% 10%	628
March	1st to 10th	Night	21% 15% 33% 23% 8%	760
	11th to 20th	Night	22% 15% 29% 29% 5%	760
	21st to end	Night	21% 12% 33% 23% 11%	820
April	1st to 10th	Night	18% 11% 31% 29% 11%	720
	11th to 20th	Night	23% 11% 32% 29% 6%	624
	21st to end	Night	19% 9% 31% 33% 8%	486
May	1st to 10th	Night	13% 9% 31% 36% 13%	360
	11th to 20th	Night	15% 6% 28% 38% 12%	354
	21st to end	Night	18% 6% 28% 38% 10%	389
June	1st to 10th	Night	24% 11% 27% 29% 8%	360
	11th to 20th	Night	21% 11% 24% 32% 11%	360
	21st to end	Night	10% 6% 33% 36% 15%	360
July	1st to 10th	Night	10% 5% 24% 50% 10% 1	350
	11th to 20th	Night	7% 4 27% 48% 14%	348
	21st to end	Night	5% 2 26% 47% 19% 1	394
August	1st to 10th	Night	6% 3 16% 47% 27%	358
	11th to 20th	Night	7% 3 19% 45% 25% 1	382
	21st to end	Night	9% 5% 23% 47% 16%	702
September	1st to 10th	Night	12% 6% 28% 38% 16%	720
	11th to 20th	Night	17% 7% 19% 36% 21% 1	720
	21st to end	Night	20% 7% 31% 30% 12%	720
October	1st to 10th	Night	20% 7% 29% 35% 9%	720
	11th to 20th	Night	27% 9% 28% 29% 7%	720
	21st to end	Night	31% 10% 33% 20% 5%	792
November	1st to 10th	Night	36% 12% 30% 17% 4	740
	11th to 20th	Night	31% 17% 28% 19% 4	818
	21st to end	Night	29% 13% 31% 21% 6%	950
December	1st to 10th	Night	27% 11% 35% 22% 5%	950
	11th to 20th	Night	29% 13% 37% 19% 3	950
	21st to end	Night	29% 13% 38% 16% 4	1045

Page generated at 2024-03-24 20:36:58. Version ac07

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