Osoyoos
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Osoyoos clear sky chart from 2005-11-06 to 2024-02-05.

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% 9% 4 6% 6% 3 5% 5% 6% 8% 39%	78208
	Night	11% 13% 4 7% 5% 3 4 5% 5% 7% 36%	80575
Transparency	Day	44% 9% 13% 20% 12% 3	77934
	Night	47% 8% 12% 19% 11% 2	80429
Seeing	Day	14% 18% 32% 25% 9% 2	13849
	Night	15% 8% 30% 32% 14% 1	22774

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	16% 24% 9% 11% 8% 4 3 4 3 5% 14%	2539
	11th to 20th	Day	16% 13% 4 8% 5% 3 5% 5% 5% 6% 29%	2516
	21st to end	Day	25% 29% 6% 7% 5% 2 3 3 3 4 15%	2794
February	1st to 10th	Day	9% 15% 5% 9% 7% 5% 5% 5% 6% 7% 28%	1527
	11th to 20th	Day	9% 12% 5% 9% 6% 4 4 5% 5% 9% 33%	1575
	21st to end	Day	8% 12% 4 9% 7% 4 6% 7% 8% 8% 29%	1480
March	1st to 10th	Day	10% 11% 4 8% 6% 4 6% 6% 7% 9% 30%	1800
	11th to 20th	Day	10% 10% 3 8% 7% 4 6% 5% 6% 9% 33%	1876
	21st to end	Day	10% 10% 4 8% 6% 4 7% 6% 7% 10% 27%	2352
April	1st to 10th	Day	9% 7% 4 8% 9% 4 7% 7% 6% 9% 30%	2160
	11th to 20th	Day	7% 8% 3 7% 7% 3 6% 6% 8% 9% 35%	2137
	21st to end	Day	7% 8% 3 6% 6% 5% 6% 6% 6% 10% 37%	2436
May	1st to 10th	Day	7% 6% 2 5% 7% 3 5% 5% 7% 9% 43%	2520
	11th to 20th	Day	9% 6% 3 6% 5% 4 5% 6% 7% 11% 38%	2477
	21st to end	Day	10% 7% 3 6% 7% 5% 7% 6% 7% 9% 33%	2723
June	1st to 10th	Day	12% 6% 3 5% 7% 4 6% 5% 7% 8% 37%	2616
	11th to 20th	Day	10% 6% 3 7% 7% 4 7% 6% 6% 10% 34%	2758
	21st to end	Day	6% 3 2 5% 6% 4 6% 5% 7% 9% 48%	2816
July	1st to 10th	Day	4 4 2 4 4 3 5% 5% 6% 9% 55%	2597
	11th to 20th	Day	3 3 2 4 4 3 4 4 5% 7% 62%	2520
	21st to end	Day	2 2 1 3 2 2 4 4 6% 7% 68%	2741
August	1st to 10th	Day	3 2 1 3 4 2 4 5% 5% 8% 63%	2507
	11th to 20th	Day	4 2 1 3 3 2 4 3 4 7% 66%	2450
	21st to end	Day	3 3 2 4 4 3 5% 5% 6% 10% 54%	2386
September	1st to 10th	Day	4 3 1 4 4 2 3 4 5% 6% 64%	2160
	11th to 20th	Day	7% 4 2 4 4 3 4 6% 7% 7% 51%	2136
	21st to end	Day	7% 6% 2 5% 4 3 5% 4 5% 8% 51%	1973
October	1st to 10th	Day	8% 5% 2 5% 5% 3 6% 5% 5% 8% 48%	1800
	11th to 20th	Day	10% 7% 3 6% 5% 3 5% 6% 5% 7% 43%	1756
	21st to end	Day	16% 10% 4 6% 4 3 4 5% 6% 6% 34%	1782
November	1st to 10th	Day	17% 11% 4 6% 7% 4 6% 5% 6% 7% 29%	1617
	11th to 20th	Day	14% 15% 6% 8% 6% 3 5% 5% 4 5% 29%	1520
	21st to end	Day	13% 18% 8% 9% 6% 2 5% 4 5% 6% 23%	1478
December	1st to 10th	Day	13% 15% 6% 9% 8% 4 5% 5% 4 6% 26%	1330
	11th to 20th	Day	12% 25% 8% 11% 6% 3 5% 4 3 4 18%	1682
	21st to end	Day	15% 19% 9% 11% 7% 4 5% 5% 5% 4 16%	2671
January	1st to 10th	Night	17% 27% 8% 11% 7% 3 4 3 3 4 13%	4406
	11th to 20th	Night	16% 15% 4 7% 5% 2 3 4 4 7% 32%	4382
	21st to end	Night	23% 31% 7% 7% 4 2 3 3 3 4 13%	4862
February	1st to 10th	Night	12% 16% 5% 9% 6% 4 5% 6% 6% 6% 25%	2524
	11th to 20th	Night	9% 12% 5% 9% 5% 3 5% 6% 5% 7% 33%	2272
	21st to end	Night	8% 13% 5% 8% 7% 3 6% 6% 7% 7% 32%	1776
March	1st to 10th	Night	11% 11% 4 8% 6% 3 5% 5% 7% 9% 31%	2160
	11th to 20th	Night	10% 9% 4 7% 6% 3 6% 7% 6% 8% 34%	2079
	21st to end	Night	8% 10% 4 8% 7% 5% 7% 6% 6% 8% 32%	2003
April	1st to 10th	Night	9% 7% 3 5% 5% 3 6% 5% 7% 10% 38%	1800
	11th to 20th	Night	6% 6% 3 7% 6% 4 5% 5% 6% 10% 42%	1773
	21st to end	Night	5% 7% 2 7% 6% 3 5% 6% 7% 9% 42%	1522
May	1st to 10th	Night	6% 5% 2 5% 4 4 5% 6% 6% 8% 48%	1440
	11th to 20th	Night	7% 5% 2 5% 5% 3 5% 5% 7% 12% 42%	1416
	21st to end	Night	8% 6% 4 7% 6% 4 6% 5% 7% 8% 40%	1552
June	1st to 10th	Night	9% 5% 4 5% 4 3 5% 7% 8% 8% 42%	1339
	11th to 20th	Night	10% 6% 2 4 4 4 5% 7% 6% 9% 42%	1195
	21st to end	Night	4 2 1 3 4 3 6% 6% 5% 10% 55%	1138
July	1st to 10th	Night	3 3 1 3 3 2 4 4 6% 8% 63%	1357
	11th to 20th	Night	2 3 1 2 2 2 3 5% 6% 8% 66%	1440
	21st to end	Night	2 1 2 2 1 2 3 5% 7% 75%	1576
August	1st to 10th	Night	3 2 1 3 4 3 4 4 4 6% 65%	1432
	11th to 20th	Night	1 2 1 2 3 2 3 3 4 6% 72%	1446
	21st to end	Night	4 2 1 3 2 2 3 5% 7% 8% 63%	1970
September	1st to 10th	Night	3 4 1 3 4 2 2 4 5% 7% 65%	1800
	11th to 20th	Night	6% 4 1 4 4 2 3 3 5% 8% 59%	1823
	21st to end	Night	7% 5% 2 5% 4 2 4 5% 5% 8% 53%	1984
October	1st to 10th	Night	10% 7% 2 3 5% 2 4 5% 6% 7% 48%	2160
	11th to 20th	Night	10% 7% 3 7% 5% 3 4 5% 6% 7% 41%	2204
	21st to end	Night	16% 9% 2 5% 4 3 4 4 5% 7% 40%	2574
November	1st to 10th	Night	18% 14% 4 5% 5% 3 4 4 5% 6% 32%	2459
	11th to 20th	Night	16% 15% 4 7% 5% 3 4 5% 5% 7% 29%	2660
	21st to end	Night	14% 18% 8% 9% 6% 3 6% 5% 4 4 24%	2680
December	1st to 10th	Night	12% 16% 7% 11% 6% 2 4 4 6% 6% 26%	2850
	11th to 20th	Night	15% 25% 7% 10% 8% 3 4 3 3 4 17%	3510
	21st to end	Night	18% 25% 6% 8% 5% 3 4 7% 5% 5% 15%	5011

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	70% 8% 7% 11% 4	2539
	11th to 20th	Day	53% 7% 15% 16% 4 5%	2540
	21st to end	Day	72% 6% 9% 9% 4	2794
February	1st to 10th	Day	54% 10% 14% 14% 6% 2	1527
	11th to 20th	Day	51% 10% 16% 16% 8%	1584
	21st to end	Day	52% 11% 13% 15% 9%	1480
March	1st to 10th	Day	50% 12% 15% 14% 8% 2	1800
	11th to 20th	Day	50% 13% 13% 18% 6%	1876
	21st to end	Day	55% 12% 16% 13% 3	2352
April	1st to 10th	Day	54% 10% 14% 16% 6% 1	2160
	11th to 20th	Day	48% 11% 12% 18% 10% 1	2137
	21st to end	Day	45% 11% 12% 19% 10% 2	2436
May	1st to 10th	Day	40% 10% 14% 25% 10% 1	2520
	11th to 20th	Day	45% 11% 14% 21% 7% 1	2480
	21st to end	Day	50% 10% 13% 20% 7% 1	2724
June	1st to 10th	Day	48% 11% 10% 17% 10% 4	2616
	11th to 20th	Day	46% 12% 12% 20% 8% 1	2758
	21st to end	Day	33% 9% 15% 24% 17% 2	2816
July	1st to 10th	Day	26% 9% 12% 25% 21% 7%	2528
	11th to 20th	Day	24% 5% 10% 24% 27% 10%	2445
	21st to end	Day	16% 5% 10% 25% 33% 11%	2589
August	1st to 10th	Day	20% 8% 11% 28% 23% 10%	2490
	11th to 20th	Day	20% 6% 12% 30% 27% 6%	2450
	21st to end	Day	26% 9% 13% 31% 19% 2	2386
September	1st to 10th	Day	23% 7% 14% 31% 21% 4	2160
	11th to 20th	Day	32% 10% 10% 25% 19% 4	2136
	21st to end	Day	34% 9% 15% 25% 15% 2	1973
October	1st to 10th	Day	35% 10% 14% 29% 12%	1800
	11th to 20th	Day	41% 10% 16% 22% 11%	1756
	21st to end	Day	48% 10% 12% 23% 7%	1782
November	1st to 10th	Day	55% 9% 13% 15% 7%	1617
	11th to 20th	Day	56% 9% 13% 15% 5% 1	1520
	21st to end	Day	59% 8% 13% 13% 6% 1	1478
December	1st to 10th	Day	54% 9% 16% 16% 5%	1330
	11th to 20th	Day	65% 9% 11% 9% 5%	1684
	21st to end	Day	66% 9% 9% 11% 5%	2671
January	1st to 10th	Night	72% 7% 8% 10% 3	4406
	11th to 20th	Night	50% 8% 12% 17% 8% 6%	4420
	21st to end	Night	74% 5% 9% 8% 3	4862
February	1st to 10th	Night	55% 10% 13% 14% 6% 2	2524
	11th to 20th	Night	49% 8% 17% 19% 7%	2274
	21st to end	Night	51% 9% 15% 16% 10%	1776
March	1st to 10th	Night	47% 11% 16% 16% 9% 1	2160
	11th to 20th	Night	48% 9% 14% 21% 8%	2080
	21st to end	Night	49% 11% 16% 18% 6%	2003
April	1st to 10th	Night	42% 12% 16% 21% 8% 1	1800
	11th to 20th	Night	41% 10% 13% 22% 12% 1	1773
	21st to end	Night	41% 9% 11% 25% 13% 1	1522
May	1st to 10th	Night	35% 9% 14% 27% 15% 1	1440
	11th to 20th	Night	36% 11% 16% 25% 10% 1	1416
	21st to end	Night	42% 9% 15% 26% 8% 1	1552
June	1st to 10th	Night	39% 9% 11% 25% 12% 3	1339
	11th to 20th	Night	37% 11% 13% 27% 11% 1	1195
	21st to end	Night	27% 9% 14% 30% 17% 3	1138
July	1st to 10th	Night	21% 7% 12% 29% 22% 9%	1317
	11th to 20th	Night	18% 7% 12% 26% 27% 9%	1392
	21st to end	Night	11% 5% 7% 30% 36% 11%	1488
August	1st to 10th	Night	19% 6% 10% 26% 30% 9%	1424
	11th to 20th	Night	15% 5% 11% 34% 31% 4	1446
	21st to end	Night	20% 7% 12% 36% 22% 4	1970
September	1st to 10th	Night	20% 7% 14% 30% 25% 4	1800
	11th to 20th	Night	26% 8% 11% 26% 24% 5%	1823
	21st to end	Night	31% 8% 15% 30% 14% 3	1984
October	1st to 10th	Night	35% 9% 14% 27% 14% 1	2160
	11th to 20th	Night	42% 8% 13% 24% 12% 1	2204
	21st to end	Night	44% 9% 13% 25% 8%	2574
November	1st to 10th	Night	54% 10% 13% 13% 8% 1	2459
	11th to 20th	Night	55% 9% 14% 14% 6% 2	2660
	21st to end	Night	61% 7% 12% 12% 6% 1	2680
December	1st to 10th	Night	55% 7% 15% 18% 4	2850
	11th to 20th	Night	68% 11% 8% 8% 5%	3507
	21st to end	Night	64% 7% 10% 12% 6% 1	5011

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	20% 16% 26% 24% 11% 3	180
	11th to 20th	Day	24% 13% 27% 20% 13% 3	180
	21st to end	Day	29% 14% 27% 23% 5% 2	198
February	1st to 10th	Day	14% 22% 46% 16% 1	223
	11th to 20th	Day	20% 17% 39% 19% 5%	335
	21st to end	Day	10% 19% 38% 25% 7% 1	346
March	1st to 10th	Day	21% 25% 28% 19% 5% 1	420
	11th to 20th	Day	17% 23% 30% 18% 11% 1	420
	21st to end	Day	20% 23% 30% 18% 7% 2	462
April	1st to 10th	Day	22% 23% 30% 17% 5% 2	420
	11th to 20th	Day	17% 28% 26% 19% 6% 3	412
	21st to end	Day	13% 26% 29% 22% 7% 3	420
May	1st to 10th	Day	12% 23% 31% 23% 9% 2	423
	11th to 20th	Day	17% 14% 33% 22% 11% 3	448
	21st to end	Day	15% 15% 31% 25% 11% 3	485
June	1st to 10th	Day	16% 18% 34% 24% 6% 1	546
	11th to 20th	Day	12% 20% 33% 26% 8% 1	688
	21st to end	Day	6% 14% 37% 29% 12% 2	746
July	1st to 10th	Day	7% 15% 33% 35% 9% 1	523
	11th to 20th	Day	7% 19% 33% 29% 10% 1	444
	21st to end	Day	3 13% 37% 32% 12% 3	487
August	1st to 10th	Day	3 13% 31% 35% 13% 4	447
	11th to 20th	Day	5% 12% 31% 32% 17% 4	437
	21st to end	Day	7% 17% 31% 31% 7% 6%	495
September	1st to 10th	Day	9% 18% 34% 24% 10% 4	450
	11th to 20th	Day	12% 16% 30% 27% 11% 4	450
	21st to end	Day	16% 20% 30% 22% 10% 2	450
October	1st to 10th	Day	13% 20% 32% 22% 12% 2	450
	11th to 20th	Day	15% 21% 24% 27% 10% 3	406
	21st to end	Day	22% 21% 28% 20% 8% 1	297
November	1st to 10th	Day	23% 15% 30% 24% 7%	243
	11th to 20th	Day	22% 20% 32% 17% 7% 2	180
	21st to end	Day	23% 18% 27% 19% 11% 2	180
December	1st to 10th	Day	24% 11% 24% 26% 13% 3	180
	11th to 20th	Day	19% 16% 30% 24% 8% 2	180
	21st to end	Day	19% 15% 30% 27% 8% 2	198
January	1st to 10th	Night	25% 10% 28% 26% 9% 2	760
	11th to 20th	Night	23% 7% 29% 29% 11% 2	760
	21st to end	Night	21% 8% 28% 29% 13% 1	836
February	1st to 10th	Night	18% 9% 34% 29% 9% 1	738
	11th to 20th	Night	14% 7% 34% 32% 12% 1	704
	21st to end	Night	12% 10% 31% 32% 14% 1	592
March	1st to 10th	Night	15% 10% 31% 29% 14% 2	720
	11th to 20th	Night	13% 10% 32% 28% 15% 1	720
	21st to end	Night	14% 10% 35% 30% 10% 1	792
April	1st to 10th	Night	13% 9% 29% 33% 15% 1	720
	11th to 20th	Night	9% 10% 36% 30% 13% 2	705
	21st to end	Night	9% 12% 39% 30% 10% 1	442
May	1st to 10th	Night	9% 9% 36% 34% 11% 1	360
	11th to 20th	Night	10% 6% 28% 33% 21% 2	354
	21st to end	Night	11% 8% 27% 38% 15%	389
June	1st to 10th	Night	12% 9% 30% 34% 14%	360
	11th to 20th	Night	14% 6% 34% 33% 12%	360
	21st to end	Night	5% 8% 32% 38% 17% 1	360
July	1st to 10th	Night	6% 4 29% 41% 19% 1	350
	11th to 20th	Night	2 7% 36% 37% 18%	348
	21st to end	Night	3 5% 27% 44% 20% 1	394
August	1st to 10th	Night	4 6% 20% 43% 27% 1	358
	11th to 20th	Night	2 3 25% 42% 25% 3	378
	21st to end	Night	5% 6% 26% 38% 23% 2	782
September	1st to 10th	Night	6% 7% 25% 36% 23% 3	720
	11th to 20th	Night	9% 6% 20% 32% 31% 3	720
	21st to end	Night	11% 7% 25% 34% 19% 3	720
October	1st to 10th	Night	15% 7% 26% 29% 20% 2	720
	11th to 20th	Night	15% 8% 28% 33% 14% 2	720
	21st to end	Night	21% 8% 26% 31% 11% 3	792
November	1st to 10th	Night	23% 9% 29% 31% 7%	740
	11th to 20th	Night	24% 10% 30% 22% 13% 2	760
	21st to end	Night	22% 10% 27% 27% 12% 2	780
December	1st to 10th	Night	18% 8% 31% 31% 11% 1	950
	11th to 20th	Night	24% 11% 31% 27% 7% 1	950
	21st to end	Night	24% 11% 30% 28% 7%	920

Page generated at 2024-02-02 02:20:27. Version ac07

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