Burns Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burns Lake clear sky chart from 2005-11-06 to 2024-09-14.

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	10% 12% 4 10% 6% 6% 5% 4 6% 7% 30%	101418
	Night	11% 13% 4 10% 6% 5% 5% 4 6% 7% 28%	96543
Transparency	Day	51% 7% 14% 20% 8% 1	101158
	Night	54% 7% 13% 17% 7% 1	96449
Seeing	Day	18% 12% 25% 24% 15% 5%	16252
	Night	18% 8% 23% 31% 17% 2	23783

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	8% 21% 8% 18% 10% 6% 7% 4 5% 4 10%	2219
	11th to 20th	Day	11% 15% 6% 10% 6% 6% 5% 4 5% 7% 26%	2199
	21st to end	Day	17% 24% 6% 14% 7% 4 5% 3 5% 5% 11%	2442
February	1st to 10th	Day	14% 15% 6% 12% 8% 4 5% 4 5% 5% 23%	1505
	11th to 20th	Day	7% 14% 5% 12% 5% 6% 6% 4 6% 8% 28%	1665
	21st to end	Day	5% 17% 6% 11% 8% 6% 7% 4 4 5% 27%	1413
March	1st to 10th	Day	7% 17% 7% 15% 8% 5% 5% 4 5% 4 23%	3142
	11th to 20th	Day	7% 15% 6% 11% 7% 7% 7% 6% 7% 8% 20%	3490
	21st to end	Day	5% 12% 5% 10% 5% 5% 5% 4 5% 6% 36%	3825
April	1st to 10th	Day	9% 17% 6% 13% 7% 5% 5% 4 5% 6% 22%	2395
	11th to 20th	Day	9% 16% 6% 12% 8% 6% 5% 4 5% 5% 25%	2438
	21st to end	Day	13% 16% 4 11% 6% 4 5% 4 5% 8% 25%	2552
May	1st to 10th	Day	9% 13% 4 11% 6% 6% 5% 4 6% 7% 30%	4543
	11th to 20th	Day	11% 13% 5% 12% 7% 7% 6% 4 5% 7% 24%	4696
	21st to end	Day	11% 11% 3 10% 7% 7% 6% 5% 7% 7% 25%	5161
June	1st to 10th	Day	14% 10% 4 10% 7% 6% 6% 4 6% 7% 28%	2997
	11th to 20th	Day	14% 10% 4 10% 6% 5% 5% 5% 6% 8% 27%	3040
	21st to end	Day	12% 8% 3 9% 7% 6% 5% 5% 6% 7% 33%	3040
July	1st to 10th	Day	7% 4 2 6% 5% 5% 4 4 6% 7% 50%	4775
	11th to 20th	Day	8% 5% 2 5% 3 4 4 4 6% 9% 51%	4740
	21st to end	Day	11% 6% 3 7% 6% 6% 6% 4 8% 9% 34%	5138
August	1st to 10th	Day	5% 4 2 4 3 3 4 3 5% 7% 58%	4719
	11th to 20th	Day	12% 6% 3 6% 5% 4 4 3 5% 7% 45%	4071
	21st to end	Day	13% 9% 3 8% 6% 6% 6% 4 6% 7% 32%	4521
September	1st to 10th	Day	13% 7% 3 8% 5% 6% 5% 5% 6% 8% 33%	2380
	11th to 20th	Day	11% 9% 3 10% 6% 6% 5% 4 6% 8% 32%	2095
	21st to end	Day	16% 11% 4 10% 6% 6% 6% 5% 6% 6% 25%	1968
October	1st to 10th	Day	13% 13% 4 10% 7% 6% 5% 4 6% 7% 26%	1800
	11th to 20th	Day	16% 13% 4 11% 7% 6% 6% 5% 7% 6% 20%	1740
	21st to end	Day	18% 14% 4 10% 6% 5% 5% 3 5% 6% 25%	1666
November	1st to 10th	Day	17% 16% 4 10% 6% 7% 4 4 6% 6% 21%	1488
	11th to 20th	Day	12% 20% 6% 10% 7% 6% 6% 4 6% 5% 17%	1444
	21st to end	Day	13% 17% 6% 13% 7% 7% 5% 4 5% 8% 17%	1307
December	1st to 10th	Day	9% 16% 3 13% 11% 7% 7% 4 6% 6% 18%	1140
	11th to 20th	Day	16% 18% 5% 13% 9% 6% 6% 4 6% 5% 13%	1442
	21st to end	Day	6% 17% 6% 13% 8% 8% 6% 5% 6% 6% 19%	2222
January	1st to 10th	Night	9% 21% 7% 17% 9% 7% 6% 4 5% 5% 10%	4726
	11th to 20th	Night	10% 16% 6% 12% 7% 5% 5% 4 5% 7% 25%	4699
	21st to end	Night	15% 22% 6% 15% 7% 7% 5% 4 4 4 11%	5214
February	1st to 10th	Night	13% 17% 6% 11% 6% 6% 5% 4 5% 5% 22%	2672
	11th to 20th	Night	8% 15% 5% 11% 5% 6% 5% 5% 5% 6% 28%	2402
	21st to end	Night	6% 14% 5% 11% 6% 6% 5% 5% 7% 5% 29%	2041
March	1st to 10th	Night	7% 14% 7% 17% 6% 5% 4 4 5% 5% 26%	3722
	11th to 20th	Night	6% 13% 5% 13% 7% 7% 6% 6% 7% 7% 25%	3489
	21st to end	Night	6% 10% 3 6% 5% 5% 5% 4 6% 7% 42%	3828
April	1st to 10th	Night	7% 14% 4 10% 7% 6% 6% 4 7% 7% 29%	1782
	11th to 20th	Night	10% 15% 4 11% 8% 6% 5% 5% 6% 7% 25%	1691
	21st to end	Night	10% 13% 4 9% 7% 4 4 4 7% 8% 29%	1627
May	1st to 10th	Night	9% 12% 3 9% 6% 5% 6% 4 7% 9% 31%	2413
	11th to 20th	Night	12% 11% 4 11% 6% 7% 6% 4 7% 8% 24%	2199
	21st to end	Night	13% 11% 4 9% 6% 6% 5% 4 7% 8% 28%	2414
June	1st to 10th	Night	12% 9% 4 9% 6% 6% 6% 6% 6% 7% 30%	1178
	11th to 20th	Night	14% 10% 4 8% 5% 5% 5% 4 7% 8% 30%	1140
	21st to end	Night	11% 6% 3 6% 5% 5% 7% 5% 6% 10% 35%	1140
July	1st to 10th	Night	7% 4 2 5% 5% 4 4 4 5% 6% 55%	2181
	11th to 20th	Night	8% 4 1 6% 4 4 6% 5% 6% 8% 49%	2220
	21st to end	Night	9% 7% 2 7% 4 4 5% 4 8% 9% 41%	2414
August	1st to 10th	Night	4 2 1 4 3 3 3 3 5% 8% 62%	2211
	11th to 20th	Night	9% 7% 3 8% 5% 4 4 4 5% 7% 45%	2765
	21st to end	Night	13% 10% 3 9% 6% 5% 5% 5% 6% 7% 32%	3146
September	1st to 10th	Night	14% 9% 3 7% 4 4 4 3 6% 7% 40%	1800
	11th to 20th	Night	10% 9% 3 8% 6% 5% 5% 5% 6% 7% 37%	1941
	21st to end	Night	17% 10% 4 7% 6% 5% 5% 5% 6% 6% 29%	1992
October	1st to 10th	Night	16% 10% 4 9% 4 5% 5% 4 4 6% 32%	2160
	11th to 20th	Night	19% 11% 4 10% 5% 5% 4 4 6% 6% 24%	2218
	21st to end	Night	17% 13% 4 7% 6% 5% 5% 4 5% 7% 28%	2690
November	1st to 10th	Night	13% 16% 5% 9% 7% 6% 5% 5% 6% 7% 20%	2590
	11th to 20th	Night	11% 18% 6% 11% 6% 6% 6% 5% 6% 7% 19%	2733
	21st to end	Night	11% 17% 6% 11% 8% 6% 5% 4 6% 7% 19%	2853
December	1st to 10th	Night	8% 14% 5% 14% 9% 6% 5% 4 6% 7% 22%	3040
	11th to 20th	Night	13% 21% 7% 12% 6% 6% 5% 4 5% 5% 16%	3750
	21st to end	Night	8% 19% 6% 12% 7% 6% 6% 5% 6% 6% 19%	5462

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	72% 10% 8% 6% 5%	2219
	11th to 20th	Day	59% 5% 14% 6% 10% 6%	2220
	21st to end	Day	75% 6% 9% 7% 3	2442
February	1st to 10th	Day	63% 6% 10% 10% 11% 1	1505
	11th to 20th	Day	54% 7% 14% 18% 6% 1	1674
	21st to end	Day	59% 5% 11% 15% 8% 2	1413
March	1st to 10th	Day	61% 7% 8% 12% 12% 1	3142
	11th to 20th	Day	56% 7% 11% 20% 5%	3490
	21st to end	Day	46% 8% 13% 24% 9%	3825
April	1st to 10th	Day	62% 5% 11% 16% 6%	2395
	11th to 20th	Day	60% 6% 9% 16% 9%	2438
	21st to end	Day	58% 5% 12% 15% 9%	2552
May	1st to 10th	Day	48% 6% 18% 16% 11%	4543
	11th to 20th	Day	56% 7% 11% 19% 6% 1	4699
	21st to end	Day	52% 7% 15% 17% 9% 1	5162
June	1st to 10th	Day	54% 6% 11% 21% 7% 1	2997
	11th to 20th	Day	54% 7% 13% 20% 6%	3040
	21st to end	Day	49% 7% 14% 25% 5%	3040
July	1st to 10th	Day	31% 6% 12% 31% 19% 1	4701
	11th to 20th	Day	29% 6% 27% 32% 6%	4659
	21st to end	Day	42% 8% 18% 23% 9%	4976
August	1st to 10th	Day	24% 7% 16% 40% 13%	4701
	11th to 20th	Day	38% 7% 15% 32% 7% 1	4111
	21st to end	Day	49% 8% 17% 20% 5%	4520
September	1st to 10th	Day	47% 8% 21% 20% 4	2380
	11th to 20th	Day	48% 8% 15% 24% 4	2095
	21st to end	Day	57% 9% 12% 17% 4	1968
October	1st to 10th	Day	57% 7% 15% 17% 4	1800
	11th to 20th	Day	61% 9% 16% 12% 2	1740
	21st to end	Day	59% 6% 15% 15% 4	1666
November	1st to 10th	Day	63% 8% 11% 14% 4	1488
	11th to 20th	Day	67% 8% 11% 11% 3	1444
	21st to end	Day	67% 8% 12% 10% 4	1307
December	1st to 10th	Day	64% 8% 13% 11% 5%	1140
	11th to 20th	Day	70% 8% 10% 8% 4	1444
	21st to end	Day	61% 9% 11% 11% 6% 1	2222
January	1st to 10th	Night	71% 9% 8% 9% 2	4726
	11th to 20th	Night	59% 5% 12% 6% 10% 7%	4740
	21st to end	Night	76% 8% 6% 7% 3	5214
February	1st to 10th	Night	63% 6% 11% 10% 9% 1	2672
	11th to 20th	Night	55% 7% 14% 16% 8%	2404
	21st to end	Night	55% 5% 11% 19% 9% 1	2041
March	1st to 10th	Night	58% 6% 9% 15% 12% 1	3722
	11th to 20th	Night	55% 8% 10% 20% 7%	3490
	21st to end	Night	38% 9% 10% 31% 11%	3828
April	1st to 10th	Night	53% 6% 14% 19% 9%	1782
	11th to 20th	Night	55% 7% 12% 19% 7%	1691
	21st to end	Night	49% 7% 13% 23% 8%	1627
May	1st to 10th	Night	44% 10% 20% 19% 8%	2413
	11th to 20th	Night	53% 10% 15% 16% 4 1	2199
	21st to end	Night	51% 7% 15% 21% 7%	2414
June	1st to 10th	Night	52% 8% 11% 20% 9% 1	1178
	11th to 20th	Night	50% 7% 12% 25% 6%	1140
	21st to end	Night	42% 9% 19% 25% 5%	1140
July	1st to 10th	Night	29% 5% 13% 28% 23% 1	2146
	11th to 20th	Night	31% 7% 26% 32% 4	2178
	21st to end	Night	37% 7% 22% 22% 11%	2337
August	1st to 10th	Night	20% 5% 18% 41% 15%	2204
	11th to 20th	Night	39% 7% 18% 28% 8%	2791
	21st to end	Night	50% 8% 22% 18% 2	3146
September	1st to 10th	Night	45% 6% 21% 22% 6%	1800
	11th to 20th	Night	45% 8% 12% 28% 7% 1	1941
	21st to end	Night	54% 8% 14% 20% 5%	1992
October	1st to 10th	Night	53% 7% 16% 19% 6%	2160
	11th to 20th	Night	58% 7% 17% 14% 4	2218
	21st to end	Night	54% 7% 16% 18% 5%	2690
November	1st to 10th	Night	61% 9% 12% 14% 5%	2590
	11th to 20th	Night	63% 8% 13% 11% 4	2733
	21st to end	Night	64% 8% 11% 12% 5%	2853
December	1st to 10th	Night	61% 7% 13% 13% 5%	3040
	11th to 20th	Night	68% 8% 10% 10% 4	3747
	21st to end	Night	62% 9% 11% 12% 6%	5462

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	19% 9% 21% 31% 14% 6%	180
	11th to 20th	Day	22% 12% 23% 25% 14% 3	180
	21st to end	Day	25% 5% 27% 25% 13% 6%	198
February	1st to 10th	Day	23% 15% 22% 27% 9% 5%	327
	11th to 20th	Day	16% 15% 28% 26% 11% 5%	365
	21st to end	Day	18% 17% 29% 19% 12% 5%	307
March	1st to 10th	Day	16% 17% 27% 24% 14% 4	400
	11th to 20th	Day	15% 13% 30% 23% 15% 3	460
	21st to end	Day	20% 13% 26% 19% 18% 4	506
April	1st to 10th	Day	21% 15% 29% 21% 10% 4	460
	11th to 20th	Day	17% 14% 25% 22% 12% 10%	452
	21st to end	Day	20% 15% 27% 21% 11% 5%	460
May	1st to 10th	Day	17% 16% 28% 23% 13% 3	534
	11th to 20th	Day	18% 12% 25% 21% 18% 6%	675
	21st to end	Day	19% 13% 26% 24% 15% 4	735
June	1st to 10th	Day	19% 13% 25% 25% 15% 3	827
	11th to 20th	Day	17% 11% 26% 27% 15% 4	870
	21st to end	Day	13% 9% 26% 28% 18% 6%	870
July	1st to 10th	Day	14% 9% 24% 28% 19% 7%	693
	11th to 20th	Day	15% 9% 26% 26% 20% 5%	668
	21st to end	Day	11% 12% 25% 28% 15% 8%	739
August	1st to 10th	Day	11% 8% 21% 26% 22% 12%	676
	11th to 20th	Day	12% 10% 25% 27% 19% 7%	481
	21st to end	Day	19% 12% 28% 22% 13% 7%	539
September	1st to 10th	Day	18% 12% 23% 24% 19% 4	490
	11th to 20th	Day	18% 9% 18% 25% 21% 9%	463
	21st to end	Day	22% 15% 31% 16% 13% 3	450
October	1st to 10th	Day	23% 14% 21% 19% 16% 7%	450
	11th to 20th	Day	24% 14% 26% 21% 11% 4	419
	21st to end	Day	25% 13% 28% 19% 14% 2	280
November	1st to 10th	Day	24% 17% 19% 22% 12% 5%	180
	11th to 20th	Day	27% 14% 21% 20% 12% 7%	180
	21st to end	Day	26% 11% 24% 17% 13% 8%	180
December	1st to 10th	Day	14% 4 22% 34% 20% 6%	180
	11th to 20th	Day	11% 9% 24% 34% 19% 3	180
	21st to end	Day	19% 9% 21% 28% 17% 6%	198
January	1st to 10th	Night	23% 9% 24% 30% 12% 2	850
	11th to 20th	Night	20% 9% 24% 31% 15% 2	850
	21st to end	Night	21% 11% 20% 31% 15% 2	935
February	1st to 10th	Night	23% 11% 22% 29% 13% 2	837
	11th to 20th	Night	16% 6% 25% 37% 13% 2	744
	21st to end	Night	12% 11% 24% 34% 16% 3	628
March	1st to 10th	Night	17% 12% 21% 30% 18% 2	760
	11th to 20th	Night	13% 11% 28% 31% 16% 1	760
	21st to end	Night	14% 10% 19% 29% 23% 4	836
April	1st to 10th	Night	13% 8% 27% 28% 22% 3	641
	11th to 20th	Night	16% 7% 25% 27% 21% 3	563
	21st to end	Night	16% 12% 25% 31% 14% 2	487
May	1st to 10th	Night	19% 8% 24% 31% 16% 1	380
	11th to 20th	Night	15% 7% 29% 26% 20% 1	374
	21st to end	Night	19% 10% 25% 27% 18% 1	411
June	1st to 10th	Night	15% 7% 26% 34% 17% 1	380
	11th to 20th	Night	17% 8% 29% 37% 9%	380
	21st to end	Night	13% 6% 27% 33% 19% 2	380
July	1st to 10th	Night	14% 7% 27% 29% 22% 2	370
	11th to 20th	Night	14% 6% 24% 32% 21% 2	368
	21st to end	Night	11% 5% 26% 37% 18% 4	416
August	1st to 10th	Night	7% 3 19% 36% 29% 6%	378
	11th to 20th	Night	11% 4 25% 32% 25% 3	533
	21st to end	Night	17% 5% 20% 35% 20% 3	627
September	1st to 10th	Night	19% 5% 19% 29% 26% 1	660
	11th to 20th	Night	13% 7% 17% 29% 29% 6%	736
	21st to end	Night	22% 10% 23% 26% 17% 2	720
October	1st to 10th	Night	23% 7% 18% 29% 19% 3	720
	11th to 20th	Night	26% 8% 21% 27% 17% 2	720
	21st to end	Night	26% 8% 23% 30% 13%	792
November	1st to 10th	Night	22% 11% 25% 26% 13% 3	740
	11th to 20th	Night	21% 12% 27% 28% 11% 2	795
	21st to end	Night	20% 9% 29% 27% 13% 3	853
December	1st to 10th	Night	15% 7% 21% 35% 18% 3	1040
	11th to 20th	Night	18% 9% 23% 34% 15% 2	1040
	21st to end	Night	17% 7% 25% 34% 15% 2	1079

Page generated at 2024-09-11 07:00:03. Version ac07

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